set hydrator enabled key when using hydrator manifests

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

fix manifests

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

.github/workflows/ci-build.yaml

@@ -370,11 +370,11 @@ jobs:
           path: test-results
       - name: combine-go-coverage
         # We generate coverage reports for all Argo CD components, but only the applicationset-controller,
-        # app-controller, and repo-server report contain coverage data. The other components currently don't shut down
-        # gracefully, so no coverage data is produced. Once those components are fixed, we can add references to their
-        # coverage output directories.
+        # app-controller, repo-server, and commit-server report contain coverage data. The other components currently
+        # don't shut down gracefully, so no coverage data is produced. Once those components are fixed, we can add
+        # references to their coverage output directories.
         run: |
-          go tool covdata percent -i=test-results,e2e-code-coverage/applicationset-controller,e2e-code-coverage/repo-server,e2e-code-coverage/app-controller -o test-results/full-coverage.out
+          go tool covdata percent -i=test-results,e2e-code-coverage/applicationset-controller,e2e-code-coverage/repo-server,e2e-code-coverage/app-controller,e2e-code-coverage/commit-server -o test-results/full-coverage.out
       - name: Upload code coverage information to codecov.io
         uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4.6.0
         with:

.mockery.yaml

@@ -26,6 +26,13 @@ packages:
   github.com/argoproj/argo-cd/v2/applicationset/utils:
     interfaces:
       Renderer:
+  github.com/argoproj/argo-cd/v2/commitserver/commit:
+    interfaces:
+      RepoClientFactory:
+  github.com/argoproj/argo-cd/v2/commitserver/apiclient:
+    interfaces:
+      CommitServiceClient:
+      Clientset:
   github.com/argoproj/argo-cd/v2/controller/cache:
     interfaces:
       LiveStateCache:

Dockerfile

@@ -140,7 +140,8 @@ RUN ln -s /usr/local/bin/argocd /usr/local/bin/argocd-server && \
     ln -s /usr/local/bin/argocd /usr/local/bin/argocd-dex && \
     ln -s /usr/local/bin/argocd /usr/local/bin/argocd-notifications && \
     ln -s /usr/local/bin/argocd /usr/local/bin/argocd-applicationset-controller && \
-    ln -s /usr/local/bin/argocd /usr/local/bin/argocd-k8s-auth
+    ln -s /usr/local/bin/argocd /usr/local/bin/argocd-k8s-auth && \
+    ln -s /usr/local/bin/argocd /usr/local/bin/argocd-commit-server
 
 USER $ARGOCD_USER_ID
 ENTRYPOINT ["/usr/bin/tini", "--"]

Makefile

@@ -472,6 +472,7 @@ start-e2e-local: mod-vendor-local dep-ui-local cli-local
 	mkdir -p /tmp/coverage/repo-server
 	mkdir -p /tmp/coverage/applicationset-controller
 	mkdir -p /tmp/coverage/notification
+	mkdir -p /tmp/coverage/commit-server
 	# set paths for locally managed ssh known hosts and tls certs data
 	ARGOCD_SSH_DATA_PATH=/tmp/argo-e2e/app/config/ssh \
 	ARGOCD_TLS_DATA_PATH=/tmp/argo-e2e/app/config/tls \

Procfile

@@ -1,9 +1,10 @@
-controller: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "GOCOVERDIR=${ARGOCD_COVERAGE_DIR:-/tmp/coverage/app-controller} HOSTNAME=testappcontroller-1  FORCE_LOG_COLORS=1 ARGOCD_FAKE_IN_CLUSTER=true ARGOCD_TLS_DATA_PATH=${ARGOCD_TLS_DATA_PATH:-/tmp/argocd-local/tls} ARGOCD_SSH_DATA_PATH=${ARGOCD_SSH_DATA_PATH:-/tmp/argocd-local/ssh} ARGOCD_BINARY_NAME=argocd-application-controller $COMMAND --loglevel debug --redis localhost:${ARGOCD_E2E_REDIS_PORT:-6379} --repo-server localhost:${ARGOCD_E2E_REPOSERVER_PORT:-8081} --otlp-address=${ARGOCD_OTLP_ADDRESS} --application-namespaces=${ARGOCD_APPLICATION_NAMESPACES:-''} --server-side-diff-enabled=${ARGOCD_APPLICATION_CONTROLLER_SERVER_SIDE_DIFF:-'false'}"
+controller: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "GOCOVERDIR=${ARGOCD_COVERAGE_DIR:-/tmp/coverage/app-controller} HOSTNAME=testappcontroller-1  FORCE_LOG_COLORS=1 ARGOCD_FAKE_IN_CLUSTER=true ARGOCD_TLS_DATA_PATH=${ARGOCD_TLS_DATA_PATH:-/tmp/argocd-local/tls} ARGOCD_SSH_DATA_PATH=${ARGOCD_SSH_DATA_PATH:-/tmp/argocd-local/ssh} ARGOCD_BINARY_NAME=argocd-application-controller $COMMAND --loglevel debug --redis localhost:${ARGOCD_E2E_REDIS_PORT:-6379} --repo-server localhost:${ARGOCD_E2E_REPOSERVER_PORT:-8081} --commit-server localhost:${ARGOCD_E2E_COMMITSERVER_PORT:-8086} --otlp-address=${ARGOCD_OTLP_ADDRESS} --application-namespaces=${ARGOCD_APPLICATION_NAMESPACES:-''} --server-side-diff-enabled=${ARGOCD_APPLICATION_CONTROLLER_SERVER_SIDE_DIFF:-'false'} --hydrator-enabled=${ARGOCD_APPLICATION_CONTROLLER_HYDRATOR_ENABLED:='false'}"
 api-server: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "GOCOVERDIR=${ARGOCD_COVERAGE_DIR:-/tmp/coverage/api-server} FORCE_LOG_COLORS=1 ARGOCD_FAKE_IN_CLUSTER=true ARGOCD_TLS_DATA_PATH=${ARGOCD_TLS_DATA_PATH:-/tmp/argocd-local/tls} ARGOCD_SSH_DATA_PATH=${ARGOCD_SSH_DATA_PATH:-/tmp/argocd-local/ssh} ARGOCD_BINARY_NAME=argocd-server $COMMAND --loglevel debug --redis localhost:${ARGOCD_E2E_REDIS_PORT:-6379} --disable-auth=${ARGOCD_E2E_DISABLE_AUTH:-'true'} --insecure --dex-server http://localhost:${ARGOCD_E2E_DEX_PORT:-5556} --repo-server localhost:${ARGOCD_E2E_REPOSERVER_PORT:-8081} --port ${ARGOCD_E2E_APISERVER_PORT:-8080} --otlp-address=${ARGOCD_OTLP_ADDRESS} --application-namespaces=${ARGOCD_APPLICATION_NAMESPACES:-''}"
 dex: sh -c "ARGOCD_BINARY_NAME=argocd-dex go run github.com/argoproj/argo-cd/v2/cmd gendexcfg -o `pwd`/dist/dex.yaml && (test -f dist/dex.yaml || { echo 'Failed to generate dex configuration'; exit 1; }) && docker run --rm -p ${ARGOCD_E2E_DEX_PORT:-5556}:${ARGOCD_E2E_DEX_PORT:-5556} -v `pwd`/dist/dex.yaml:/dex.yaml ghcr.io/dexidp/dex:$(grep "image: ghcr.io/dexidp/dex" manifests/base/dex/argocd-dex-server-deployment.yaml | cut -d':' -f3) dex serve /dex.yaml"
 redis: hack/start-redis-with-password.sh
 repo-server: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "GOCOVERDIR=${ARGOCD_COVERAGE_DIR:-/tmp/coverage/repo-server} FORCE_LOG_COLORS=1 ARGOCD_FAKE_IN_CLUSTER=true ARGOCD_GNUPGHOME=${ARGOCD_GNUPGHOME:-/tmp/argocd-local/gpg/keys} ARGOCD_PLUGINSOCKFILEPATH=${ARGOCD_PLUGINSOCKFILEPATH:-./test/cmp}  ARGOCD_GPG_DATA_PATH=${ARGOCD_GPG_DATA_PATH:-/tmp/argocd-local/gpg/source} ARGOCD_TLS_DATA_PATH=${ARGOCD_TLS_DATA_PATH:-/tmp/argocd-local/tls} ARGOCD_SSH_DATA_PATH=${ARGOCD_SSH_DATA_PATH:-/tmp/argocd-local/ssh} ARGOCD_BINARY_NAME=argocd-repo-server ARGOCD_GPG_ENABLED=${ARGOCD_GPG_ENABLED:-false} $COMMAND --loglevel debug --port ${ARGOCD_E2E_REPOSERVER_PORT:-8081} --redis localhost:${ARGOCD_E2E_REDIS_PORT:-6379} --otlp-address=${ARGOCD_OTLP_ADDRESS}"
 cmp-server: [ "$ARGOCD_E2E_TEST" = 'true' ] && exit 0 || [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "FORCE_LOG_COLORS=1 ARGOCD_FAKE_IN_CLUSTER=true ARGOCD_BINARY_NAME=argocd-cmp-server ARGOCD_PLUGINSOCKFILEPATH=${ARGOCD_PLUGINSOCKFILEPATH:-./test/cmp} $COMMAND --config-dir-path ./test/cmp --loglevel debug --otlp-address=${ARGOCD_OTLP_ADDRESS}"
+commit-server: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "GOCOVERDIR=${ARGOCD_COVERAGE_DIR:-/tmp/coverage/commit-server} FORCE_LOG_COLORS=1 ARGOCD_BINARY_NAME=argocd-commit-server $COMMAND --loglevel debug --port ${ARGOCD_E2E_COMMITSERVER_PORT:-8086}"
 ui: sh -c 'cd ui && ${ARGOCD_E2E_YARN_CMD:-yarn} start'
 git-server: test/fixture/testrepos/start-git.sh
 helm-registry: test/fixture/testrepos/start-helm-registry.sh

applicationset/services/internal/github_app/client.go

@@ -5,7 +5,7 @@ import (
 	"net/http"
 
 	"github.com/bradleyfalzon/ghinstallation/v2"
-	"github.com/google/go-github/v63/github"
+	"github.com/google/go-github/v66/github"
 
 	"github.com/argoproj/argo-cd/v2/applicationset/services/github_app_auth"
 )

applicationset/services/pull_request/github.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/google/go-github/v63/github"
+	"github.com/google/go-github/v66/github"
 	"golang.org/x/oauth2"
 )
 

applicationset/services/pull_request/github_test.go

@@ -3,7 +3,7 @@ package pull_request
 import (
 	"testing"
 
-	"github.com/google/go-github/v63/github"
+	"github.com/google/go-github/v66/github"
 	"github.com/stretchr/testify/require"
 )
 

applicationset/services/scm_provider/github.go

@@ -6,7 +6,7 @@ import (
 	"net/http"
 	"os"
 
-	"github.com/google/go-github/v63/github"
+	"github.com/google/go-github/v66/github"
 	"golang.org/x/oauth2"
 )
 

assets/swagger.json

@@ -6857,6 +6857,9 @@
         "source": {
           "$ref": "#/definitions/v1alpha1ApplicationSource"
         },
+        "sourceHydrator": {
+          "$ref": "#/definitions/v1alpha1SourceHydrator"
+        },
         "sources": {
           "type": "array",
           "title": "Sources is a reference to the location of the application's manifests or chart",
@@ -6914,6 +6917,9 @@
             "$ref": "#/definitions/applicationv1alpha1ResourceStatus"
           }
         },
+        "sourceHydrator": {
+          "$ref": "#/definitions/v1alpha1SourceHydratorStatus"
+        },
         "sourceType": {
           "type": "string",
           "title": "SourceType specifies the type of this application"
@@ -7341,6 +7347,24 @@
         }
       }
     },
+    "v1alpha1DrySource": {
+      "description": "DrySource specifies a location for dry \"don't repeat yourself\" manifest source information.",
+      "type": "object",
+      "properties": {
+        "path": {
+          "type": "string",
+          "title": "Path is a directory path within the Git repository where the manifests are located"
+        },
+        "repoURL": {
+          "type": "string",
+          "title": "RepoURL is the URL to the git repository that contains the application manifests"
+        },
+        "targetRevision": {
+          "type": "string",
+          "title": "TargetRevision defines the revision of the source to hydrate"
+        }
+      }
+    },
     "v1alpha1DuckTypeGenerator": {
       "description": "DuckType defines a generator to match against clusters registered with ArgoCD.",
       "type": "object",
@@ -7595,6 +7619,47 @@
         }
       }
     },
+    "v1alpha1HydrateOperation": {
+      "type": "object",
+      "title": "HydrateOperation contains information about the most recent hydrate operation",
+      "properties": {
+        "drySHA": {
+          "type": "string",
+          "title": "DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation"
+        },
+        "finishedAt": {
+          "$ref": "#/definitions/v1Time"
+        },
+        "hydratedSHA": {
+          "type": "string",
+          "title": "HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation"
+        },
+        "message": {
+          "type": "string",
+          "title": "Message contains a message describing the current status of the hydrate operation"
+        },
+        "phase": {
+          "type": "string",
+          "title": "Phase indicates the status of the hydrate operation"
+        },
+        "sourceHydrator": {
+          "$ref": "#/definitions/v1alpha1SourceHydrator"
+        },
+        "startedAt": {
+          "$ref": "#/definitions/v1Time"
+        }
+      }
+    },
+    "v1alpha1HydrateTo": {
+      "description": "HydrateTo specifies a location to which hydrated manifests should be pushed as a \"staging area\" before being moved to\nthe SyncSource. The RepoURL and Path are assumed based on the associated SyncSource config in the SourceHydrator.",
+      "type": "object",
+      "properties": {
+        "targetBranch": {
+          "type": "string",
+          "title": "TargetBranch is the branch to which hydrated manifests should be committed"
+        }
+      }
+    },
     "v1alpha1Info": {
       "type": "object",
       "properties": {
@@ -9202,6 +9267,50 @@
         }
       }
     },
+    "v1alpha1SourceHydrator": {
+      "description": "SourceHydrator specifies a dry \"don't repeat yourself\" source for manifests, a sync source from which to sync\nhydrated manifests, and an optional hydrateTo location to act as a \"staging\" aread for hydrated manifests.",
+      "type": "object",
+      "properties": {
+        "drySource": {
+          "$ref": "#/definitions/v1alpha1DrySource"
+        },
+        "hydrateTo": {
+          "$ref": "#/definitions/v1alpha1HydrateTo"
+        },
+        "syncSource": {
+          "$ref": "#/definitions/v1alpha1SyncSource"
+        }
+      }
+    },
+    "v1alpha1SourceHydratorStatus": {
+      "type": "object",
+      "title": "SourceHydratorStatus contains information about the current state of source hydration",
+      "properties": {
+        "currentOperation": {
+          "$ref": "#/definitions/v1alpha1HydrateOperation"
+        },
+        "lastSuccessfulOperation": {
+          "$ref": "#/definitions/v1alpha1SuccessfulHydrateOperation"
+        }
+      }
+    },
+    "v1alpha1SuccessfulHydrateOperation": {
+      "type": "object",
+      "title": "SuccessfulHydrateOperation contains information about the most recent successful hydrate operation",
+      "properties": {
+        "drySHA": {
+          "type": "string",
+          "title": "DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation"
+        },
+        "hydratedSHA": {
+          "type": "string",
+          "title": "HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation"
+        },
+        "sourceHydrator": {
+          "$ref": "#/definitions/v1alpha1SourceHydrator"
+        }
+      }
+    },
     "v1alpha1SyncOperation": {
       "description": "SyncOperation contains details about a sync operation.",
       "type": "object",
@@ -9361,6 +9470,20 @@
         }
       }
     },
+    "v1alpha1SyncSource": {
+      "description": "SyncSource specifies a location from which hydrated manifests may be synced. RepoURL is assumed based on the\nassociated DrySource config in the SourceHydrator.",
+      "type": "object",
+      "properties": {
+        "path": {
+          "description": "Path is a directory path within the git repository where hydrated manifests should be committed to and synced\nfrom. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.",
+          "type": "string"
+        },
+        "targetBranch": {
+          "type": "string",
+          "title": "TargetBranch is the branch to which hydrated manifests should be committed"
+        }
+      }
+    },
     "v1alpha1SyncStatus": {
       "type": "object",
       "title": "SyncStatus contains information about the currently observed live and desired states of an application",

cmd/argocd-application-controller/commands/argocd_application_controller.go

@@ -19,6 +19,7 @@ import (
 	"k8s.io/client-go/tools/clientcmd"
 
 	cmdutil "github.com/argoproj/argo-cd/v2/cmd/util"
+	commitclient "github.com/argoproj/argo-cd/v2/commitserver/apiclient"
 	"github.com/argoproj/argo-cd/v2/common"
 	"github.com/argoproj/argo-cd/v2/controller"
 	"github.com/argoproj/argo-cd/v2/controller/sharding"
@@ -58,6 +59,7 @@ func NewCommand() *cobra.Command {
 		repoErrorGracePeriod             int64
 		repoServerAddress                string
 		repoServerTimeoutSeconds         int
+		commitServerAddress              string
 		selfHealTimeoutSeconds           int
 		selfHealBackoffTimeoutSeconds    int
 		selfHealBackoffFactor            int
@@ -87,7 +89,8 @@ func NewCommand() *cobra.Command {
 		ignoreNormalizerOpts             normalizers.IgnoreNormalizerOpts
 
 		// argocd k8s event logging flag
-		enableK8sEvent []string
+		enableK8sEvent  []string
+		hydratorEnabled bool
 	)
 	command := cobra.Command{
 		Use:               cliName,
@@ -157,6 +160,8 @@ func NewCommand() *cobra.Command {
 
 			repoClientset := apiclient.NewRepoServerClientset(repoServerAddress, repoServerTimeoutSeconds, tlsConfig)
 
+			commitClientset := commitclient.NewCommitServerClientset(commitServerAddress)
+
 			cache, err := cacheSource()
 			errors.CheckError(err)
 			cache.Cache.SetClient(cacheutil.NewTwoLevelClient(cache.Cache.GetClient(), 10*time.Minute))
@@ -183,6 +188,7 @@ func NewCommand() *cobra.Command {
 				kubeClient,
 				appClient,
 				repoClientset,
+				commitClientset,
 				cache,
 				kubectl,
 				resyncDuration,
@@ -205,6 +211,7 @@ func NewCommand() *cobra.Command {
 				enableDynamicClusterDistribution,
 				ignoreNormalizerOpts,
 				enableK8sEvent,
+				hydratorEnabled,
 			)
 			errors.CheckError(err)
 			cacheutil.CollectMetrics(redisClient, appController.GetMetricsServer(), nil)
@@ -247,6 +254,7 @@ func NewCommand() *cobra.Command {
 	command.Flags().Int64Var(&repoErrorGracePeriod, "repo-error-grace-period-seconds", int64(env.ParseDurationFromEnv("ARGOCD_REPO_ERROR_GRACE_PERIOD_SECONDS", defaultAppResyncPeriod*time.Second, 0, math.MaxInt64).Seconds()), "Grace period in seconds for ignoring consecutive errors while communicating with repo server.")
 	command.Flags().StringVar(&repoServerAddress, "repo-server", env.StringFromEnv("ARGOCD_APPLICATION_CONTROLLER_REPO_SERVER", common.DefaultRepoServerAddr), "Repo server address.")
 	command.Flags().IntVar(&repoServerTimeoutSeconds, "repo-server-timeout-seconds", env.ParseNumFromEnv("ARGOCD_APPLICATION_CONTROLLER_REPO_SERVER_TIMEOUT_SECONDS", 60, 0, math.MaxInt64), "Repo server RPC call timeout seconds.")
+	command.Flags().StringVar(&commitServerAddress, "commit-server", env.StringFromEnv("ARGOCD_APPLICATION_CONTROLLER_COMMIT_SERVER", common.DefaultCommitServerAddr), "Commit server address.")
 	command.Flags().IntVar(&statusProcessors, "status-processors", env.ParseNumFromEnv("ARGOCD_APPLICATION_CONTROLLER_STATUS_PROCESSORS", 20, 0, math.MaxInt32), "Number of application status processors")
 	command.Flags().IntVar(&operationProcessors, "operation-processors", env.ParseNumFromEnv("ARGOCD_APPLICATION_CONTROLLER_OPERATION_PROCESSORS", 10, 0, math.MaxInt32), "Number of application operation processors")
 	command.Flags().StringVar(&cmdutil.LogFormat, "logformat", env.StringFromEnv("ARGOCD_APPLICATION_CONTROLLER_LOGFORMAT", "text"), "Set the logging format. One of: text|json")
@@ -285,7 +293,7 @@ func NewCommand() *cobra.Command {
 	command.Flags().DurationVar(&ignoreNormalizerOpts.JQExecutionTimeout, "ignore-normalizer-jq-execution-timeout-seconds", env.ParseDurationFromEnv("ARGOCD_IGNORE_NORMALIZER_JQ_TIMEOUT", 0*time.Second, 0, math.MaxInt64), "Set ignore normalizer JQ execution timeout")
 	// argocd k8s event logging flag
 	command.Flags().StringSliceVar(&enableK8sEvent, "enable-k8s-event", env.StringsFromEnv("ARGOCD_ENABLE_K8S_EVENT", argo.DefaultEnableEventList(), ","), "Enable ArgoCD to use k8s event. For disabling all events, set the value as `none`. (e.g --enable-k8s-event=none), For enabling specific events, set the value as `event reason`. (e.g --enable-k8s-event=StatusRefreshed,ResourceCreated)")
-
+	command.Flags().BoolVar(&hydratorEnabled, "hydrator-enabled", env.ParseBoolFromEnv("ARGOCD_HYDRATOR_ENABLED", false), "Feature flag to enable Hydrator. Default (\"false\")")
 	cacheSource = appstatecache.AddCacheFlagsToCmd(&command, cacheutil.Options{
 		OnClientCreated: func(client *redis.Client) {
 			redisClient = client

cmd/argocd-commit-server/commands/argocd_commit_server.go

@@ -0,0 +1,117 @@
+package commands
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"google.golang.org/grpc/health/grpc_health_v1"
+
+	cmdutil "github.com/argoproj/argo-cd/v2/cmd/util"
+	"github.com/argoproj/argo-cd/v2/commitserver"
+	"github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	"github.com/argoproj/argo-cd/v2/commitserver/metrics"
+	"github.com/argoproj/argo-cd/v2/common"
+	"github.com/argoproj/argo-cd/v2/util/askpass"
+	"github.com/argoproj/argo-cd/v2/util/cli"
+	"github.com/argoproj/argo-cd/v2/util/env"
+	"github.com/argoproj/argo-cd/v2/util/errors"
+	"github.com/argoproj/argo-cd/v2/util/healthz"
+	ioutil "github.com/argoproj/argo-cd/v2/util/io"
+)
+
+// NewCommand returns a new instance of an argocd-commit-server command
+func NewCommand() *cobra.Command {
+	var (
+		listenHost  string
+		listenPort  int
+		metricsPort int
+		metricsHost string
+	)
+	command := &cobra.Command{
+		Use:   "argocd-commit-server",
+		Short: "Run Argo CD Commit Server",
+		Long:  "Argo CD Commit Server is an internal service which commits and pushes hydrated manifests to git. This command runs Commit Server in the foreground.",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			vers := common.GetVersion()
+			vers.LogStartupInfo(
+				"Argo CD Commit Server",
+				map[string]any{
+					"port": listenPort,
+				},
+			)
+
+			cli.SetLogFormat(cmdutil.LogFormat)
+			cli.SetLogLevel(cmdutil.LogLevel)
+
+			metricsServer := metrics.NewMetricsServer()
+			http.Handle("/metrics", metricsServer.GetHandler())
+			go func() { errors.CheckError(http.ListenAndServe(fmt.Sprintf("%s:%d", metricsHost, metricsPort), nil)) }()
+
+			askPassServer := askpass.NewServer(askpass.CommitServerSocketPath)
+			go func() { errors.CheckError(askPassServer.Run()) }()
+
+			server := commitserver.NewServer(askPassServer, metricsServer)
+			grpc := server.CreateGRPC()
+
+			listener, err := net.Listen("tcp", fmt.Sprintf("%s:%d", listenHost, listenPort))
+			errors.CheckError(err)
+
+			healthz.ServeHealthCheck(http.DefaultServeMux, func(r *http.Request) error {
+				if val, ok := r.URL.Query()["full"]; ok && len(val) > 0 && val[0] == "true" {
+					// connect to itself to make sure commit server is able to serve connection
+					// used by liveness probe to auto restart commit server
+					conn, err := apiclient.NewConnection(fmt.Sprintf("localhost:%d", listenPort))
+					if err != nil {
+						return err
+					}
+					defer ioutil.Close(conn)
+					client := grpc_health_v1.NewHealthClient(conn)
+					res, err := client.Check(r.Context(), &grpc_health_v1.HealthCheckRequest{})
+					if err != nil {
+						return err
+					}
+					if res.Status != grpc_health_v1.HealthCheckResponse_SERVING {
+						return fmt.Errorf("grpc health check status is '%v'", res.Status)
+					}
+					return nil
+				}
+				return nil
+			})
+
+			// Graceful shutdown code adapted from here: https://gist.github.com/embano1/e0bf49d24f1cdd07cffad93097c04f0a
+			sigCh := make(chan os.Signal, 1)
+			signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+			wg := sync.WaitGroup{}
+			wg.Add(1)
+			go func() {
+				s := <-sigCh
+				log.Printf("got signal %v, attempting graceful shutdown", s)
+				grpc.GracefulStop()
+				wg.Done()
+			}()
+
+			log.Println("starting grpc server")
+			err = grpc.Serve(listener)
+			errors.CheckError(err)
+			wg.Wait()
+			log.Println("clean shutdown")
+
+			return nil
+		},
+	}
+	command.Flags().StringVar(&cmdutil.LogFormat, "logformat", env.StringFromEnv("ARGOCD_COMMIT_SERVER_LOGFORMAT", "text"), "Set the logging format. One of: text|json")
+	command.Flags().StringVar(&cmdutil.LogLevel, "loglevel", env.StringFromEnv("ARGOCD_COMMIT_SERVER_LOGLEVEL", "info"), "Set the logging level. One of: debug|info|warn|error")
+	command.Flags().StringVar(&listenHost, "address", env.StringFromEnv("ARGOCD_COMMIT_SERVER_LISTEN_ADDRESS", common.DefaultAddressCommitServer), "Listen on given address for incoming connections")
+	command.Flags().IntVar(&listenPort, "port", common.DefaultPortCommitServer, "Listen on given port for incoming connections")
+	command.Flags().StringVar(&metricsHost, "metrics-address", env.StringFromEnv("ARGOCD_COMMIT_SERVER_METRICS_LISTEN_ADDRESS", common.DefaultAddressCommitServerMetrics), "Listen on given address for metrics")
+	command.Flags().IntVar(&metricsPort, "metrics-port", common.DefaultPortCommitServerMetrics, "Start metrics server on given port")
+
+	return command
+}

cmd/argocd-git-ask-pass/commands/argocd_git_ask_pass.go

@@ -9,7 +9,7 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 
-	"github.com/argoproj/argo-cd/v2/reposerver/askpass"
+	"github.com/argoproj/argo-cd/v2/util/askpass"
 	"github.com/argoproj/argo-cd/v2/util/errors"
 	grpc_util "github.com/argoproj/argo-cd/v2/util/grpc"
 	"github.com/argoproj/argo-cd/v2/util/io"

cmd/argocd-repo-server/commands/argocd_repo_server.go

@@ -23,10 +23,10 @@ import (
 	"github.com/argoproj/argo-cd/v2/common"
 	"github.com/argoproj/argo-cd/v2/reposerver"
 	"github.com/argoproj/argo-cd/v2/reposerver/apiclient"
-	"github.com/argoproj/argo-cd/v2/reposerver/askpass"
 	reposervercache "github.com/argoproj/argo-cd/v2/reposerver/cache"
 	"github.com/argoproj/argo-cd/v2/reposerver/metrics"
 	"github.com/argoproj/argo-cd/v2/reposerver/repository"
+	"github.com/argoproj/argo-cd/v2/util/askpass"
 	cacheutil "github.com/argoproj/argo-cd/v2/util/cache"
 	"github.com/argoproj/argo-cd/v2/util/cli"
 	"github.com/argoproj/argo-cd/v2/util/env"

cmd/argocd/commands/app.go

@@ -112,6 +112,7 @@ type watchOpts struct {
 	suspended bool
 	degraded  bool
 	delete    bool
+	hydrated  bool
 }
 
 // NewApplicationCreateCommand returns a new instance of an `argocd app create` command
@@ -1883,6 +1884,7 @@ func NewApplicationWaitCommand(clientOpts *argocdclient.ClientOptions) *cobra.Co
 	command.Flags().BoolVar(&watch.suspended, "suspended", false, "Wait for suspended")
 	command.Flags().BoolVar(&watch.degraded, "degraded", false, "Wait for degraded")
 	command.Flags().BoolVar(&watch.delete, "delete", false, "Wait for delete")
+	command.Flags().BoolVar(&watch.hydrated, "hydrated", false, "Wait for hydration operations")
 	command.Flags().StringVarP(&selector, "selector", "l", "", "Wait for apps by label. Supports '=', '==', '!=', in, notin, exists & not exists. Matching apps must satisfy all of the specified label constraints.")
 	command.Flags().StringArrayVar(&resources, "resource", []string{}, fmt.Sprintf("Sync only specific resources as GROUP%[1]sKIND%[1]sNAME or %[2]sGROUP%[1]sKIND%[1]sNAME. Fields may be blank and '*' can be used. This option may be specified repeatedly", resourceFieldDelimiter, resourceExcludeIndicator))
 	command.Flags().BoolVar(&watch.operation, "operation", false, "Wait for pending operations")
@@ -2450,7 +2452,7 @@ func groupResourceStates(app *argoappv1.Application, selectedResources []*argoap
 }
 
 // check if resource health, sync and operation statuses matches watch options
-func checkResourceStatus(watch watchOpts, healthStatus string, syncStatus string, operationStatus *argoappv1.Operation) bool {
+func checkResourceStatus(watch watchOpts, healthStatus string, syncStatus string, operationStatus *argoappv1.Operation, hydrationFinished bool) bool {
 	if watch.delete {
 		return false
 	}
@@ -2480,7 +2482,8 @@ func checkResourceStatus(watch watchOpts, healthStatus string, syncStatus string
 
 	synced := !watch.sync || syncStatus == string(argoappv1.SyncStatusCodeSynced)
 	operational := !watch.operation || operationStatus == nil
-	return synced && healthCheckPassed && operational
+	hydration := !watch.hydrated || hydrationFinished
+	return synced && healthCheckPassed && operational && hydration
 }
 
 // resourceParentChild gets the latest state of the app and the latest state of the app's resource tree and then
@@ -2644,13 +2647,15 @@ func waitOnApplicationStatus(ctx context.Context, acdClient argocdclient.Client,
 			}
 		}
 
+		hydrationFinished := app.Status.SourceHydrator.CurrentOperation != nil && app.Status.SourceHydrator.CurrentOperation.Phase == argoappv1.HydrateOperationPhaseHydrated && app.Status.SourceHydrator.CurrentOperation.SourceHydrator.DeepEquals(app.Status.SourceHydrator.LastSuccessfulOperation.SourceHydrator) && app.Status.SourceHydrator.CurrentOperation.DrySHA == app.Status.SourceHydrator.LastSuccessfulOperation.DrySHA
+
 		var selectedResourcesAreReady bool
 
 		// If selected resources are included, wait only on those resources, otherwise wait on the application as a whole.
 		if len(selectedResources) > 0 {
 			selectedResourcesAreReady = true
 			for _, state := range getResourceStates(app, selectedResources) {
-				resourceIsReady := checkResourceStatus(watch, state.Health, state.Status, appEvent.Application.Operation)
+				resourceIsReady := checkResourceStatus(watch, state.Health, state.Status, appEvent.Application.Operation, hydrationFinished)
 				if !resourceIsReady {
 					selectedResourcesAreReady = false
 					break
@@ -2658,7 +2663,7 @@ func waitOnApplicationStatus(ctx context.Context, acdClient argocdclient.Client,
 			}
 		} else {
 			// Wait on the application as a whole
-			selectedResourcesAreReady = checkResourceStatus(watch, string(app.Status.Health.Status), string(app.Status.Sync.Status), appEvent.Application.Operation)
+			selectedResourcesAreReady = checkResourceStatus(watch, string(app.Status.Health.Status), string(app.Status.Sync.Status), appEvent.Application.Operation, hydrationFinished)
 		}
 
 		if selectedResourcesAreReady && (!operationInProgress || !watch.operation) {

cmd/argocd/commands/app_test.go

@@ -1705,7 +1705,7 @@ func TestCheckResourceStatus(t *testing.T) {
 			suspended: true,
 			health:    true,
 			degraded:  true,
-		}, string(health.HealthStatusHealthy), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusHealthy), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Degraded, Suspended and health status failed", func(t *testing.T) {
@@ -1713,57 +1713,57 @@ func TestCheckResourceStatus(t *testing.T) {
 			suspended: true,
 			health:    true,
 			degraded:  true,
-		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.False(t, res)
 	})
 	t.Run("Suspended and health status passed", func(t *testing.T) {
 		res := checkResourceStatus(watchOpts{
 			suspended: true,
 			health:    true,
-		}, string(health.HealthStatusHealthy), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusHealthy), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Suspended and health status failed", func(t *testing.T) {
 		res := checkResourceStatus(watchOpts{
 			suspended: true,
 			health:    true,
-		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.False(t, res)
 	})
 	t.Run("Suspended passed", func(t *testing.T) {
 		res := checkResourceStatus(watchOpts{
 			suspended: true,
 			health:    false,
-		}, string(health.HealthStatusSuspended), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusSuspended), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Suspended failed", func(t *testing.T) {
 		res := checkResourceStatus(watchOpts{
 			suspended: true,
 			health:    false,
-		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.False(t, res)
 	})
 	t.Run("Health passed", func(t *testing.T) {
 		res := checkResourceStatus(watchOpts{
 			suspended: false,
 			health:    true,
-		}, string(health.HealthStatusHealthy), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusHealthy), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Health failed", func(t *testing.T) {
 		res := checkResourceStatus(watchOpts{
 			suspended: false,
 			health:    true,
-		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.False(t, res)
 	})
 	t.Run("Synced passed", func(t *testing.T) {
-		res := checkResourceStatus(watchOpts{}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		res := checkResourceStatus(watchOpts{}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Synced failed", func(t *testing.T) {
-		res := checkResourceStatus(watchOpts{}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeOutOfSync), &v1alpha1.Operation{})
+		res := checkResourceStatus(watchOpts{}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeOutOfSync), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Degraded passed", func(t *testing.T) {
@@ -1771,7 +1771,7 @@ func TestCheckResourceStatus(t *testing.T) {
 			suspended: false,
 			health:    false,
 			degraded:  true,
-		}, string(health.HealthStatusDegraded), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusDegraded), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.True(t, res)
 	})
 	t.Run("Degraded failed", func(t *testing.T) {
@@ -1779,7 +1779,7 @@ func TestCheckResourceStatus(t *testing.T) {
 			suspended: false,
 			health:    false,
 			degraded:  true,
-		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{})
+		}, string(health.HealthStatusProgressing), string(v1alpha1.SyncStatusCodeSynced), &v1alpha1.Operation{}, true)
 		assert.False(t, res)
 	})
 }

cmd/main.go

@@ -11,6 +11,7 @@ import (
 	appcontroller "github.com/argoproj/argo-cd/v2/cmd/argocd-application-controller/commands"
 	applicationset "github.com/argoproj/argo-cd/v2/cmd/argocd-applicationset-controller/commands"
 	cmpserver "github.com/argoproj/argo-cd/v2/cmd/argocd-cmp-server/commands"
+	commitserver "github.com/argoproj/argo-cd/v2/cmd/argocd-commit-server/commands"
 	dex "github.com/argoproj/argo-cd/v2/cmd/argocd-dex/commands"
 	gitaskpass "github.com/argoproj/argo-cd/v2/cmd/argocd-git-ask-pass/commands"
 	k8sauth "github.com/argoproj/argo-cd/v2/cmd/argocd-k8s-auth/commands"
@@ -46,6 +47,8 @@ func main() {
 	case "argocd-cmp-server":
 		command = cmpserver.NewCommand()
 		isCLI = true
+	case "argocd-commit-server":
+		command = commitserver.NewCommand()
 	case "argocd-dex":
 		command = dex.NewCommand()
 	case "argocd-notifications":

cmd/util/app.go

@@ -91,6 +91,12 @@ type AppOptions struct {
 	retryBackoffFactor              int64
 	ref                             string
 	SourceName                      string
+	drySourceRepo                   string
+	drySourceRevision               string
+	drySourcePath                   string
+	syncSourceBranch                string
+	syncSourcePath                  string
+	hydrateToBranch                 string
 }
 
 // SetAutoMaxProcs sets the GOMAXPROCS value based on the binary name.
@@ -112,6 +118,12 @@ func AddAppFlags(command *cobra.Command, opts *AppOptions) {
 	command.Flags().StringVar(&opts.chart, "helm-chart", "", "Helm Chart name")
 	command.Flags().StringVar(&opts.env, "env", "", "Application environment to monitor")
 	command.Flags().StringVar(&opts.revision, "revision", "", "The tracking source branch, tag, commit or Helm chart version the application will sync to")
+	command.Flags().StringVar(&opts.drySourceRepo, "dry-source-repo", "", "Repository URL of the app dry source")
+	command.Flags().StringVar(&opts.drySourceRevision, "dry-source-revision", "", "Revision of the app dry source")
+	command.Flags().StringVar(&opts.drySourcePath, "dry-source-path", "", "Path in repository to the app directory for the dry source")
+	command.Flags().StringVar(&opts.syncSourceBranch, "sync-source-branch", "", "The branch from which the app will sync")
+	command.Flags().StringVar(&opts.syncSourcePath, "sync-source-path", "", "The path in the repository from which the app will sync")
+	command.Flags().StringVar(&opts.hydrateToBranch, "hydrate-to-branch", "", "The branch to hydrate the app to")
 	command.Flags().IntVar(&opts.revisionHistoryLimit, "revision-history-limit", argoappv1.RevisionHistoryLimit, "How many items to keep in revision history")
 	command.Flags().StringVar(&opts.destServer, "dest-server", "", "K8s cluster URL (e.g. https://kubernetes.default.svc)")
 	command.Flags().StringVar(&opts.destName, "dest-name", "", "K8s cluster Name (e.g. minikube)")
@@ -175,21 +187,27 @@ func SetAppSpecOptions(flags *pflag.FlagSet, spec *argoappv1.ApplicationSpec, ap
 	if flags == nil {
 		return visited
 	}
-	source := spec.GetSourcePtrByPosition(sourcePosition)
-	if source == nil {
-		source = &argoappv1.ApplicationSource{}
-	}
-	source, visited = ConstructSource(source, *appOpts, flags)
-	if spec.HasMultipleSources() {
-		if sourcePosition == 0 {
-			spec.Sources[sourcePosition] = *source
-		} else if sourcePosition > 0 {
-			spec.Sources[sourcePosition-1] = *source
-		} else {
-			spec.Sources = append(spec.Sources, *source)
-		}
+	var h *argoappv1.SourceHydrator
+	h, hasHydratorFlag := constructSourceHydrator(spec.SourceHydrator, *appOpts, flags)
+	if hasHydratorFlag {
+		spec.SourceHydrator = h
 	} else {
-		spec.Source = source
+		source := spec.GetSourcePtrByPosition(sourcePosition)
+		if source == nil {
+			source = &argoappv1.ApplicationSource{}
+		}
+		source, visited = ConstructSource(source, *appOpts, flags)
+		if spec.HasMultipleSources() {
+			if sourcePosition == 0 {
+				spec.Sources[sourcePosition] = *source
+			} else if sourcePosition > 0 {
+				spec.Sources[sourcePosition-1] = *source
+			} else {
+				spec.Sources = append(spec.Sources, *source)
+			}
+		} else {
+			spec.Source = source
+		}
 	}
 	flags.Visit(func(f *pflag.Flag) {
 		visited++
@@ -592,9 +610,7 @@ func constructAppsBaseOnName(appName string, labels, annotations, args []string,
 			Name:      appName,
 			Namespace: appNs,
 		},
-		Spec: argoappv1.ApplicationSpec{
-			Source: &argoappv1.ApplicationSource{},
-		},
+		Spec: argoappv1.ApplicationSpec{},
 	}
 	SetAppSpecOptions(flags, &app.Spec, &appOpts, 0)
 	SetParameterOverrides(app, appOpts.Parameters, 0)
@@ -768,6 +784,47 @@ func ConstructSource(source *argoappv1.ApplicationSource, appOpts AppOptions, fl
 	return source, visited
 }
 
+// constructSourceHydrator constructs a source hydrator from the command line flags. It returns the modified source
+// hydrator and a boolean indicating if any hydrator flags were set. We return instead of just modifying the source
+// hydrator in place because the given hydrator `h` might be nil. In that case, we need to create a new source hydrator
+// and return it.
+func constructSourceHydrator(h *argoappv1.SourceHydrator, appOpts AppOptions, flags *pflag.FlagSet) (*argoappv1.SourceHydrator, bool) {
+	hasHydratorFlag := false
+	ensureNotNil := func(notEmpty bool) {
+		hasHydratorFlag = true
+		if notEmpty && h == nil {
+			h = &argoappv1.SourceHydrator{}
+		}
+	}
+	flags.Visit(func(f *pflag.Flag) {
+		switch f.Name {
+		case "dry-source-repo":
+			ensureNotNil(appOpts.drySourceRepo != "")
+			h.DrySource.RepoURL = appOpts.drySourceRepo
+		case "dry-source-path":
+			ensureNotNil(appOpts.drySourcePath != "")
+			h.DrySource.Path = appOpts.drySourcePath
+		case "dry-source-revision":
+			ensureNotNil(appOpts.drySourceRevision != "")
+			h.DrySource.TargetRevision = appOpts.drySourceRevision
+		case "sync-source-branch":
+			ensureNotNil(appOpts.syncSourceBranch != "")
+			h.SyncSource.TargetBranch = appOpts.syncSourceBranch
+		case "sync-source-path":
+			ensureNotNil(appOpts.syncSourcePath != "")
+			h.SyncSource.Path = appOpts.syncSourcePath
+		case "hydrate-to-branch":
+			ensureNotNil(appOpts.hydrateToBranch != "")
+			if appOpts.hydrateToBranch == "" {
+				h.HydrateTo = nil
+			} else {
+				h.HydrateTo = &argoappv1.HydrateTo{TargetBranch: appOpts.hydrateToBranch}
+			}
+		}
+	})
+	return h, hasHydratorFlag
+}
+
 func mergeLabels(app *argoappv1.Application, labels []string) {
 	mapLabels, err := label.Parse(labels)
 	errors.CheckError(err)

cmd/util/app_test.go

@@ -295,6 +295,28 @@ func Test_setAppSpecOptions(t *testing.T) {
 		require.NoError(t, f.SetFlag("helm-api-versions", "v2"))
 		assert.Equal(t, []string{"v1", "v2"}, f.spec.Source.Helm.APIVersions)
 	})
+	t.Run("source hydrator", func(t *testing.T) {
+		require.NoError(t, f.SetFlag("dry-source-repo", "https://github.com/argoproj/argocd-example-apps"))
+		assert.Equal(t, "https://github.com/argoproj/argocd-example-apps", f.spec.SourceHydrator.DrySource.RepoURL)
+
+		require.NoError(t, f.SetFlag("dry-source-path", "apps"))
+		assert.Equal(t, "apps", f.spec.SourceHydrator.DrySource.Path)
+
+		require.NoError(t, f.SetFlag("dry-source-revision", "HEAD"))
+		assert.Equal(t, "HEAD", f.spec.SourceHydrator.DrySource.TargetRevision)
+
+		require.NoError(t, f.SetFlag("sync-source-branch", "env/test"))
+		assert.Equal(t, "env/test", f.spec.SourceHydrator.SyncSource.TargetBranch)
+
+		require.NoError(t, f.SetFlag("sync-source-path", "apps"))
+		assert.Equal(t, "apps", f.spec.SourceHydrator.SyncSource.Path)
+
+		require.NoError(t, f.SetFlag("hydrate-to-branch", "env/test-next"))
+		assert.Equal(t, "env/test-next", f.spec.SourceHydrator.HydrateTo.TargetBranch)
+
+		require.NoError(t, f.SetFlag("hydrate-to-branch", ""))
+		assert.Nil(t, f.spec.SourceHydrator.HydrateTo)
+	})
 }
 
 func newMultiSourceAppOptionsFixture() *appOptionsFixture {

commitserver/apiclient/clientset.go

@@ -0,0 +1,49 @@
+package apiclient
+
+import (
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/insecure"
+
+	"github.com/argoproj/argo-cd/v2/util/io"
+)
+
+// Clientset represents commit server api clients
+type Clientset interface {
+	NewCommitServerClient() (io.Closer, CommitServiceClient, error)
+}
+
+type clientSet struct {
+	address string
+}
+
+// NewCommitServerClient creates new instance of commit server client
+func (c *clientSet) NewCommitServerClient() (io.Closer, CommitServiceClient, error) {
+	conn, err := NewConnection(c.address)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to open a new connection to commit server: %w", err)
+	}
+	return conn, NewCommitServiceClient(conn), nil
+}
+
+// NewConnection creates new connection to commit server
+func NewConnection(address string) (*grpc.ClientConn, error) {
+	var opts []grpc.DialOption
+	opts = append(opts, grpc.WithTransportCredentials(insecure.NewCredentials()))
+
+	// TODO: switch to grpc.NewClient.
+	// nolint:staticcheck
+	conn, err := grpc.Dial(address, opts...)
+	if err != nil {
+		log.Errorf("Unable to connect to commit service with address %s", address)
+		return nil, err
+	}
+	return conn, nil
+}
+
+// NewCommitServerClientset creates new instance of commit server Clientset
+func NewCommitServerClientset(address string) Clientset {
+	return &clientSet{address: address}
+}

commitserver/apiclient/mocks/Clientset.go

@@ -0,0 +1,68 @@
+// Code generated by mockery v2.43.2. DO NOT EDIT.
+
+package mocks
+
+import (
+	apiclient "github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	io "github.com/argoproj/argo-cd/v2/util/io"
+
+	mock "github.com/stretchr/testify/mock"
+)
+
+// Clientset is an autogenerated mock type for the Clientset type
+type Clientset struct {
+	mock.Mock
+}
+
+// NewCommitServerClient provides a mock function with given fields:
+func (_m *Clientset) NewCommitServerClient() (io.Closer, apiclient.CommitServiceClient, error) {
+	ret := _m.Called()
+
+	if len(ret) == 0 {
+		panic("no return value specified for NewCommitServerClient")
+	}
+
+	var r0 io.Closer
+	var r1 apiclient.CommitServiceClient
+	var r2 error
+	if rf, ok := ret.Get(0).(func() (io.Closer, apiclient.CommitServiceClient, error)); ok {
+		return rf()
+	}
+	if rf, ok := ret.Get(0).(func() io.Closer); ok {
+		r0 = rf()
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(io.Closer)
+		}
+	}
+
+	if rf, ok := ret.Get(1).(func() apiclient.CommitServiceClient); ok {
+		r1 = rf()
+	} else {
+		if ret.Get(1) != nil {
+			r1 = ret.Get(1).(apiclient.CommitServiceClient)
+		}
+	}
+
+	if rf, ok := ret.Get(2).(func() error); ok {
+		r2 = rf()
+	} else {
+		r2 = ret.Error(2)
+	}
+
+	return r0, r1, r2
+}
+
+// NewClientset creates a new instance of Clientset. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
+// The first argument is typically a *testing.T value.
+func NewClientset(t interface {
+	mock.TestingT
+	Cleanup(func())
+}) *Clientset {
+	mock := &Clientset{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}

commitserver/apiclient/mocks/CommitServiceClient.go

@@ -0,0 +1,69 @@
+// Code generated by mockery v2.43.2. DO NOT EDIT.
+
+package mocks
+
+import (
+	context "context"
+
+	apiclient "github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+
+	grpc "google.golang.org/grpc"
+
+	mock "github.com/stretchr/testify/mock"
+)
+
+// CommitServiceClient is an autogenerated mock type for the CommitServiceClient type
+type CommitServiceClient struct {
+	mock.Mock
+}
+
+// CommitHydratedManifests provides a mock function with given fields: ctx, in, opts
+func (_m *CommitServiceClient) CommitHydratedManifests(ctx context.Context, in *apiclient.CommitHydratedManifestsRequest, opts ...grpc.CallOption) (*apiclient.CommitHydratedManifestsResponse, error) {
+	_va := make([]interface{}, len(opts))
+	for _i := range opts {
+		_va[_i] = opts[_i]
+	}
+	var _ca []interface{}
+	_ca = append(_ca, ctx, in)
+	_ca = append(_ca, _va...)
+	ret := _m.Called(_ca...)
+
+	if len(ret) == 0 {
+		panic("no return value specified for CommitHydratedManifests")
+	}
+
+	var r0 *apiclient.CommitHydratedManifestsResponse
+	var r1 error
+	if rf, ok := ret.Get(0).(func(context.Context, *apiclient.CommitHydratedManifestsRequest, ...grpc.CallOption) (*apiclient.CommitHydratedManifestsResponse, error)); ok {
+		return rf(ctx, in, opts...)
+	}
+	if rf, ok := ret.Get(0).(func(context.Context, *apiclient.CommitHydratedManifestsRequest, ...grpc.CallOption) *apiclient.CommitHydratedManifestsResponse); ok {
+		r0 = rf(ctx, in, opts...)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(*apiclient.CommitHydratedManifestsResponse)
+		}
+	}
+
+	if rf, ok := ret.Get(1).(func(context.Context, *apiclient.CommitHydratedManifestsRequest, ...grpc.CallOption) error); ok {
+		r1 = rf(ctx, in, opts...)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
+// NewCommitServiceClient creates a new instance of CommitServiceClient. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
+// The first argument is typically a *testing.T value.
+func NewCommitServiceClient(t interface {
+	mock.TestingT
+	Cleanup(func())
+}) *CommitServiceClient {
+	mock := &CommitServiceClient{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}

commitserver/commit/commit.go

@@ -0,0 +1,225 @@
+package commit
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	"github.com/argoproj/argo-cd/v2/commitserver/metrics"
+	"github.com/argoproj/argo-cd/v2/util/git"
+	"github.com/argoproj/argo-cd/v2/util/io/files"
+)
+
+// Service is the service that handles commit requests.
+type Service struct {
+	gitCredsStore     git.CredsStore
+	metricsServer     *metrics.Server
+	repoClientFactory RepoClientFactory
+}
+
+// NewService returns a new instance of the commit service.
+func NewService(gitCredsStore git.CredsStore, metricsServer *metrics.Server) *Service {
+	return &Service{
+		gitCredsStore:     gitCredsStore,
+		metricsServer:     metricsServer,
+		repoClientFactory: NewRepoClientFactory(gitCredsStore, metricsServer),
+	}
+}
+
+// CommitHydratedManifests handles a commit request. It clones the repository, checks out the sync branch, checks out
+// the target branch, clears the repository contents, writes the manifests to the repository, commits the changes, and
+// pushes the changes. It returns the hydrated revision SHA and an error if one occurred.
+func (s *Service) CommitHydratedManifests(ctx context.Context, r *apiclient.CommitHydratedManifestsRequest) (*apiclient.CommitHydratedManifestsResponse, error) {
+	// This method is intentionally short. It's a wrapper around handleCommitRequest that adds metrics and logging.
+	// Keep logic here minimal and put most of the logic in handleCommitRequest.
+	startTime := time.Now()
+
+	// We validate for a nil repo in handleCommitRequest, but we need to check for a nil repo here to get the repo URL
+	// for metrics.
+	var repoURL string
+	if r.Repo != nil {
+		repoURL = r.Repo.Repo
+	}
+
+	var err error
+	s.metricsServer.IncPendingCommitRequest(repoURL)
+	defer func() {
+		s.metricsServer.DecPendingCommitRequest(repoURL)
+		commitResponseType := metrics.CommitResponseTypeSuccess
+		if err != nil {
+			commitResponseType = metrics.CommitResponseTypeFailure
+		}
+		s.metricsServer.IncCommitRequest(repoURL, commitResponseType)
+		s.metricsServer.ObserveCommitRequestDuration(repoURL, commitResponseType, time.Since(startTime))
+	}()
+
+	logCtx := log.WithFields(log.Fields{"branch": r.TargetBranch, "drySHA": r.DrySha})
+
+	out, sha, err := s.handleCommitRequest(logCtx, r)
+	if err != nil {
+		logCtx.WithError(err).WithField("output", out).Error("failed to handle commit request")
+
+		// No need to wrap this error, sufficient context is build in handleCommitRequest.
+		return &apiclient.CommitHydratedManifestsResponse{}, err
+	}
+
+	logCtx.Info("Successfully handled commit request")
+	return &apiclient.CommitHydratedManifestsResponse{
+		HydratedSha: sha,
+	}, nil
+}
+
+// handleCommitRequest handles the commit request. It clones the repository, checks out the sync branch, checks out the
+// target branch, clears the repository contents, writes the manifests to the repository, commits the changes, and pushes
+// the changes. It returns the output of the git commands and an error if one occurred.
+func (s *Service) handleCommitRequest(logCtx *log.Entry, r *apiclient.CommitHydratedManifestsRequest) (string, string, error) {
+	if r.Repo == nil {
+		return "", "", fmt.Errorf("repo is required")
+	}
+	if r.Repo.Repo == "" {
+		return "", "", fmt.Errorf("repo URL is required")
+	}
+	if r.TargetBranch == "" {
+		return "", "", fmt.Errorf("target branch is required")
+	}
+	if r.SyncBranch == "" {
+		return "", "", fmt.Errorf("sync branch is required")
+	}
+
+	logCtx = logCtx.WithField("repo", r.Repo.Repo)
+	logCtx.Debug("Initiating git client")
+	gitClient, dirPath, cleanup, err := s.initGitClient(logCtx, r)
+	if err != nil {
+		return "", "", fmt.Errorf("failed to init git client: %w", err)
+	}
+	defer cleanup()
+
+	logCtx.Debugf("Checking out sync branch %s", r.SyncBranch)
+	var out string
+	out, err = gitClient.CheckoutOrOrphan(r.SyncBranch, false)
+	if err != nil {
+		return out, "", fmt.Errorf("failed to checkout sync branch: %w", err)
+	}
+
+	logCtx.Debugf("Checking out target branch %s", r.TargetBranch)
+	out, err = gitClient.CheckoutOrNew(r.TargetBranch, r.SyncBranch, false)
+	if err != nil {
+		return out, "", fmt.Errorf("failed to checkout target branch: %w", err)
+	}
+
+	logCtx.Debug("Clearing repo contents")
+	out, err = gitClient.RemoveContents()
+	if err != nil {
+		return out, "", fmt.Errorf("failed to clear repo: %w", err)
+	}
+
+	logCtx.Debug("Writing manifests")
+	err = WriteForPaths(dirPath, r.Repo.Repo, r.DrySha, r.Paths)
+	if err != nil {
+		return "", "", fmt.Errorf("failed to write manifests: %w", err)
+	}
+
+	logCtx.Debug("Committing and pushing changes")
+	out, err = gitClient.CommitAndPush(r.TargetBranch, r.CommitMessage)
+	if err != nil {
+		return out, "", fmt.Errorf("failed to commit and push: %w", err)
+	}
+
+	logCtx.Debug("Getting commit SHA")
+	sha, err := gitClient.CommitSHA()
+	if err != nil {
+		return "", "", fmt.Errorf("failed to get commit SHA: %w", err)
+	}
+
+	return "", sha, nil
+}
+
+// initGitClient initializes a git client for the given repository and returns the client, the path to the directory where
+// the repository is cloned, a cleanup function that should be called when the directory is no longer needed, and an error
+// if one occurred.
+func (s *Service) initGitClient(logCtx *log.Entry, r *apiclient.CommitHydratedManifestsRequest) (git.Client, string, func(), error) {
+	dirPath, err := files.CreateTempDir("/tmp/_commit-service")
+	if err != nil {
+		return nil, "", nil, fmt.Errorf("failed to create temp dir: %w", err)
+	}
+	// Call cleanupOrLog in this function if an error occurs to ensure the temp dir is cleaned up.
+	cleanupOrLog := func() {
+		err := os.RemoveAll(dirPath)
+		if err != nil {
+			logCtx.WithError(err).Error("failed to cleanup temp dir")
+		}
+	}
+
+	gitClient, err := s.repoClientFactory.NewClient(r.Repo, dirPath)
+	if err != nil {
+		cleanupOrLog()
+		return nil, "", nil, fmt.Errorf("failed to create git client: %w", err)
+	}
+
+	logCtx.Debugf("Initializing repo %s", r.Repo.Repo)
+	err = gitClient.Init()
+	if err != nil {
+		cleanupOrLog()
+		return nil, "", nil, fmt.Errorf("failed to init git client: %w", err)
+	}
+
+	logCtx.Debugf("Fetching repo %s", r.Repo.Repo)
+	err = gitClient.Fetch("")
+	if err != nil {
+		cleanupOrLog()
+		return nil, "", nil, fmt.Errorf("failed to clone repo: %w", err)
+	}
+
+	// FIXME: make it work for GHE
+	//logCtx.Debugf("Getting user info for repo credentials")
+	//gitCreds := r.Repo.GetGitCreds(s.gitCredsStore)
+	//startTime := time.Now()
+	//authorName, authorEmail, err := gitCreds.GetUserInfo(ctx)
+	//s.metricsServer.ObserveUserInfoRequestDuration(r.Repo.Repo, getCredentialType(r.Repo), time.Since(startTime))
+	//if err != nil {
+	//	cleanupOrLog()
+	//	return nil, "", nil, fmt.Errorf("failed to get github app info: %w", err)
+	//}
+	var authorName, authorEmail string
+
+	if authorName == "" {
+		authorName = "Argo CD"
+	}
+	if authorEmail == "" {
+		logCtx.Warnf("Author email not available, using 'argo-cd@example.com'.")
+		authorEmail = "argo-cd@example.com"
+	}
+
+	logCtx.Debugf("Setting author %s <%s>", authorName, authorEmail)
+	_, err = gitClient.SetAuthor(authorName, authorEmail)
+	if err != nil {
+		cleanupOrLog()
+		return nil, "", nil, fmt.Errorf("failed to set author: %w", err)
+	}
+
+	return gitClient, dirPath, cleanupOrLog, nil
+}
+
+type hydratorMetadataFile struct {
+	RepoURL  string   `json:"repoURL"`
+	DrySHA   string   `json:"drySha"`
+	Commands []string `json:"commands"`
+}
+
+// TODO: make this configurable via ConfigMap.
+var manifestHydrationReadmeTemplate = `
+# Manifest Hydration
+
+To hydrate the manifests in this repository, run the following commands:
+
+` + "```shell\n" + `
+git clone {{ .RepoURL }}
+# cd into the cloned directory
+git checkout {{ .DrySHA }}
+{{ range $command := .Commands -}}
+{{ $command }}
+{{ end -}}` + "```"

commitserver/commit/commit.proto

@@ -0,0 +1,50 @@
+syntax = "proto3";
+option go_package = "github.com/argoproj/argo-cd/v2/commitserver/apiclient";
+
+import "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1/generated.proto";
+
+// CommitHydratedManifestsRequest is the request to commit hydrated manifests to a repository.
+message CommitHydratedManifestsRequest {
+  // Repo contains repository information including, at minimum, the URL of the repository. Generally it will contain
+  // repo credentials.
+  github.com.argoproj.argo_cd.v2.pkg.apis.application.v1alpha1.Repository repo = 1;
+  // SyncBranch is the branch Argo CD syncs from, i.e. the hydrated branch.
+  string syncBranch = 2;
+  // TargetBranch is the branch Argo CD is committing to, i.e. the branch that will be updated.
+  string targetBranch = 3;
+  // DrySha is the commit SHA from the dry branch, i.e. pre-rendered manifest branch.
+  string drySha = 4;
+  // CommitMessage is the commit message to use when committing changes.
+  string commitMessage = 5;
+  // Paths contains the paths to write hydrated manifests to, along with the manifests and commands to execute.
+  repeated PathDetails paths = 6;
+}
+
+// PathDetails holds information about hydrated manifests to be written to a particular path in the hydrated manifests
+// commit.
+message PathDetails {
+  // Path is the path to write the hydrated manifests to.
+  string path = 1;
+  // Manifests contains the manifests to write to the path.
+  repeated HydratedManifestDetails manifests = 2;
+  // Commands contains the commands executed when hydrating the manifests.
+  repeated string commands = 3;
+}
+
+// ManifestDetails contains the hydrated manifests.
+message HydratedManifestDetails {
+  // ManifestJSON is the hydrated manifest as JSON.
+  string manifestJSON = 1;
+}
+
+// ManifestsResponse is the response to the ManifestsRequest.
+message CommitHydratedManifestsResponse {
+  // HydratedSha is the commit SHA of the hydrated manifests commit.
+  string hydratedSha = 1;
+}
+
+// CommitService is the service for committing hydrated manifests to a repository.
+service CommitService {
+  // Commit commits hydrated manifests to a repository.
+  rpc CommitHydratedManifests (CommitHydratedManifestsRequest) returns (CommitHydratedManifestsResponse);
+}

commitserver/commit/commit_test.go

@@ -0,0 +1,125 @@
+package commit
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+
+	"github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	"github.com/argoproj/argo-cd/v2/commitserver/commit/mocks"
+	"github.com/argoproj/argo-cd/v2/commitserver/metrics"
+	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+	"github.com/argoproj/argo-cd/v2/util/git"
+	gitmocks "github.com/argoproj/argo-cd/v2/util/git/mocks"
+)
+
+func Test_CommitHydratedManifests(t *testing.T) {
+	t.Parallel()
+
+	validRequest := &apiclient.CommitHydratedManifestsRequest{
+		Repo: &v1alpha1.Repository{
+			Repo: "https://github.com/argoproj/argocd-example-apps.git",
+		},
+		TargetBranch:  "main",
+		SyncBranch:    "env/test",
+		CommitMessage: "test commit message",
+	}
+
+	t.Run("missing repo", func(t *testing.T) {
+		t.Parallel()
+
+		service, _ := newServiceWithMocks(t)
+		request := &apiclient.CommitHydratedManifestsRequest{}
+		_, err := service.CommitHydratedManifests(context.Background(), request)
+		require.Error(t, err)
+		assert.ErrorContains(t, err, "repo is required")
+	})
+
+	t.Run("missing repo URL", func(t *testing.T) {
+		t.Parallel()
+
+		service, _ := newServiceWithMocks(t)
+		request := &apiclient.CommitHydratedManifestsRequest{
+			Repo: &v1alpha1.Repository{},
+		}
+		_, err := service.CommitHydratedManifests(context.Background(), request)
+		require.Error(t, err)
+		assert.ErrorContains(t, err, "repo URL is required")
+	})
+
+	t.Run("missing target branch", func(t *testing.T) {
+		t.Parallel()
+
+		service, _ := newServiceWithMocks(t)
+		request := &apiclient.CommitHydratedManifestsRequest{
+			Repo: &v1alpha1.Repository{
+				Repo: "https://github.com/argoproj/argocd-example-apps.git",
+			},
+		}
+		_, err := service.CommitHydratedManifests(context.Background(), request)
+		require.Error(t, err)
+		assert.ErrorContains(t, err, "target branch is required")
+	})
+
+	t.Run("missing sync branch", func(t *testing.T) {
+		t.Parallel()
+
+		service, _ := newServiceWithMocks(t)
+		request := &apiclient.CommitHydratedManifestsRequest{
+			Repo: &v1alpha1.Repository{
+				Repo: "https://github.com/argoproj/argocd-example-apps.git",
+			},
+			TargetBranch: "main",
+		}
+		_, err := service.CommitHydratedManifests(context.Background(), request)
+		require.Error(t, err)
+		assert.ErrorContains(t, err, "sync branch is required")
+	})
+
+	t.Run("failed to create git client", func(t *testing.T) {
+		t.Parallel()
+
+		service, mockRepoClientFactory := newServiceWithMocks(t)
+		mockRepoClientFactory.On("NewClient", mock.Anything, mock.Anything).Return(nil, assert.AnError).Once()
+
+		_, err := service.CommitHydratedManifests(context.Background(), validRequest)
+		require.Error(t, err)
+		assert.ErrorIs(t, err, assert.AnError)
+	})
+
+	t.Run("happy path", func(t *testing.T) {
+		t.Parallel()
+
+		service, mockRepoClientFactory := newServiceWithMocks(t)
+		mockGitClient := gitmocks.NewClient(t)
+		mockGitClient.On("Init").Return(nil).Once()
+		mockGitClient.On("Fetch", mock.Anything).Return(nil).Once()
+		mockGitClient.On("SetAuthor", "Argo CD", "argo-cd@example.com").Return("", nil).Once()
+		mockGitClient.On("CheckoutOrOrphan", "env/test", false).Return("", nil).Once()
+		mockGitClient.On("CheckoutOrNew", "main", "env/test", false).Return("", nil).Once()
+		mockGitClient.On("RemoveContents").Return("", nil).Once()
+		mockGitClient.On("CommitAndPush", "main", "test commit message").Return("", nil).Once()
+		mockGitClient.On("CommitSHA").Return("it-worked!", nil).Once()
+		mockRepoClientFactory.On("NewClient", mock.Anything, mock.Anything).Return(mockGitClient, nil).Once()
+
+		resp, err := service.CommitHydratedManifests(context.Background(), validRequest)
+		require.NoError(t, err)
+		require.NotNil(t, resp)
+		assert.Equal(t, "it-worked!", resp.HydratedSha)
+	})
+}
+
+func newServiceWithMocks(t *testing.T) (*Service, *mocks.RepoClientFactory) {
+	t.Helper()
+
+	metricsServer := metrics.NewMetricsServer()
+	mockCredsStore := git.NoopCredsStore{}
+	service := NewService(mockCredsStore, metricsServer)
+	mockRepoClientFactory := mocks.NewRepoClientFactory(t)
+	service.repoClientFactory = mockRepoClientFactory
+
+	return service, mockRepoClientFactory
+}

commitserver/commit/credentialtypehelper.go

@@ -0,0 +1,23 @@
+package commit
+
+import "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+
+// getCredentialType returns the type of credential used by the repository.
+func getCredentialType(repo *v1alpha1.Repository) string {
+	if repo == nil {
+		return ""
+	}
+	if repo.Password != "" {
+		return "https"
+	}
+	if repo.SSHPrivateKey != "" {
+		return "ssh"
+	}
+	if repo.GithubAppPrivateKey != "" && repo.GithubAppId != 0 && repo.GithubAppInstallationId != 0 {
+		return "github-app"
+	}
+	if repo.GCPServiceAccountKey != "" {
+		return "cloud-source-repositories"
+	}
+	return ""
+}

commitserver/commit/credentialtypehelper_test.go

@@ -0,0 +1,62 @@
+package commit
+
+import (
+	"testing"
+
+	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+)
+
+func TestRepository_GetCredentialType(t *testing.T) {
+	tests := []struct {
+		name string
+		repo *v1alpha1.Repository
+		want string
+	}{
+		{
+			name: "Empty Repository",
+			repo: nil,
+			want: "",
+		},
+		{
+			name: "HTTPS Repository",
+			repo: &v1alpha1.Repository{
+				Repo:     "foo",
+				Password: "some-password",
+			},
+			want: "https",
+		},
+		{
+			name: "SSH Repository",
+			repo: &v1alpha1.Repository{
+				Repo:          "foo",
+				SSHPrivateKey: "some-key",
+			},
+			want: "ssh",
+		},
+		{
+			name: "GitHub App Repository",
+			repo: &v1alpha1.Repository{
+				Repo:                    "foo",
+				GithubAppPrivateKey:     "some-key",
+				GithubAppId:             1,
+				GithubAppInstallationId: 1,
+			},
+			want: "github-app",
+		},
+		{
+			name: "Google Cloud Repository",
+			repo: &v1alpha1.Repository{
+				Repo:                 "foo",
+				GCPServiceAccountKey: "some-key",
+			},
+			want: "cloud-source-repositories",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := getCredentialType(tt.repo); got != tt.want {
+				t.Errorf("Repository.GetCredentialType() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

commitserver/commit/hydratorhelper.go

@@ -0,0 +1,145 @@
+package commit
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path"
+	"text/template"
+
+	log "github.com/sirupsen/logrus"
+	"gopkg.in/yaml.v3"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+
+	"github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	"github.com/argoproj/argo-cd/v2/util/io/files"
+)
+
+// WriteForPaths writes the manifests, hydrator.metadata, and README.md files for each path in the provided paths. It
+// also writes a root-level hydrator.metadata file containing the repo URL and dry SHA.
+func WriteForPaths(rootPath string, repoUrl string, drySha string, paths []*apiclient.PathDetails) error {
+	// Write the top-level readme.
+	err := writeMetadata(rootPath, hydratorMetadataFile{DrySHA: drySha, RepoURL: repoUrl})
+	if err != nil {
+		return fmt.Errorf("failed to write top-level hydrator metadata: %w", err)
+	}
+
+	for _, p := range paths {
+		hydratePath := p.Path
+		if hydratePath == "." {
+			hydratePath = ""
+		}
+
+		var fullHydratePath string
+		fullHydratePath, err = files.SecureMkdirAll(rootPath, hydratePath, os.ModePerm)
+		if err != nil {
+			return fmt.Errorf("failed to create path: %w", err)
+		}
+
+		// Write the manifests
+		err = writeManifests(fullHydratePath, p.Manifests)
+		if err != nil {
+			return fmt.Errorf("failed to write manifests: %w", err)
+		}
+
+		// Write hydrator.metadata containing information about the hydration process.
+		hydratorMetadata := hydratorMetadataFile{
+			Commands: p.Commands,
+			DrySHA:   drySha,
+			RepoURL:  repoUrl,
+		}
+		err = writeMetadata(fullHydratePath, hydratorMetadata)
+		if err != nil {
+			return fmt.Errorf("failed to write hydrator metadata: %w", err)
+		}
+
+		// Write README
+		err = writeReadme(fullHydratePath, hydratorMetadata)
+		if err != nil {
+			return fmt.Errorf("failed to write readme: %w", err)
+		}
+	}
+	return nil
+}
+
+// writeMetadata writes the metadata to the hydrator.metadata file.
+func writeMetadata(dirPath string, metadata hydratorMetadataFile) error {
+	hydratorMetadataJson, err := json.MarshalIndent(metadata, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal hydrator metadata: %w", err)
+	}
+	// No need to use SecureJoin here, as the path is already sanitized.
+	hydratorMetadataPath := path.Join(dirPath, "hydrator.metadata")
+	err = os.WriteFile(hydratorMetadataPath, hydratorMetadataJson, os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("failed to write hydrator metadata: %w", err)
+	}
+	return nil
+}
+
+// writeReadme writes the readme to the README.md file.
+func writeReadme(dirPath string, metadata hydratorMetadataFile) error {
+	readmeTemplate := template.New("readme")
+	readmeTemplate, err := readmeTemplate.Parse(manifestHydrationReadmeTemplate)
+	if err != nil {
+		return fmt.Errorf("failed to parse readme template: %w", err)
+	}
+	// Create writer to template into
+	// No need to use SecureJoin here, as the path is already sanitized.
+	readmePath := path.Join(dirPath, "README.md")
+	readmeFile, err := os.Create(readmePath)
+	if err != nil && !os.IsExist(err) {
+		return fmt.Errorf("failed to create README file: %w", err)
+	}
+	err = readmeTemplate.Execute(readmeFile, metadata)
+	closeErr := readmeFile.Close()
+	if closeErr != nil {
+		log.WithError(closeErr).Error("failed to close README file")
+	}
+	if err != nil {
+		return fmt.Errorf("failed to execute readme template: %w", err)
+	}
+	return nil
+}
+
+// writeManifests writes the manifests to the manifest.yaml file, truncating the file if it exists and appending the
+// manifests in the order they are provided.
+func writeManifests(dirPath string, manifests []*apiclient.HydratedManifestDetails) error {
+	// If the file exists, truncate it.
+	// No need to use SecureJoin here, as the path is already sanitized.
+	manifestPath := path.Join(dirPath, "manifest.yaml")
+
+	file, err := os.OpenFile(manifestPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("failed to open manifest file: %w", err)
+	}
+	defer func() {
+		err := file.Close()
+		if err != nil {
+			log.WithError(err).Error("failed to close file")
+		}
+	}()
+
+	enc := yaml.NewEncoder(file)
+	defer func() {
+		err := enc.Close()
+		if err != nil {
+			log.WithError(err).Error("failed to close yaml encoder")
+		}
+	}()
+	enc.SetIndent(2)
+
+	for _, m := range manifests {
+		obj := &unstructured.Unstructured{}
+		err = json.Unmarshal([]byte(m.ManifestJSON), obj)
+		if err != nil {
+			return fmt.Errorf("failed to unmarshal manifest: %w", err)
+		}
+		err = enc.Encode(&obj.Object)
+		if err != nil {
+			return fmt.Errorf("failed to encode manifest: %w", err)
+		}
+	}
+
+	return nil
+}

commitserver/commit/hydratorhelper_test.go

@@ -0,0 +1,135 @@
+package commit
+
+import (
+	"encoding/json"
+	"os"
+	"path"
+	"testing"
+
+	securejoin "github.com/cyphar/filepath-securejoin"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+)
+
+func TestWriteForPaths(t *testing.T) {
+	dir := t.TempDir()
+
+	repoUrl := "https://github.com/example/repo"
+	drySha := "abc123"
+	paths := []*apiclient.PathDetails{
+		{
+			Path: "path1",
+			Manifests: []*apiclient.HydratedManifestDetails{
+				{ManifestJSON: `{"kind":"Pod","apiVersion":"v1"}`},
+			},
+			Commands: []string{"command1", "command2"},
+		},
+		{
+			Path: "path2",
+			Manifests: []*apiclient.HydratedManifestDetails{
+				{ManifestJSON: `{"kind":"Service","apiVersion":"v1"}`},
+			},
+			Commands: []string{"command3"},
+		},
+	}
+
+	err := WriteForPaths(dir, repoUrl, drySha, paths)
+	require.NoError(t, err)
+
+	// Check if the top-level hydrator.metadata exists and contains the repo URL and dry SHA
+	topMetadataPath := path.Join(dir, "hydrator.metadata")
+	topMetadataBytes, err := os.ReadFile(topMetadataPath)
+	require.NoError(t, err)
+
+	var topMetadata hydratorMetadataFile
+	err = json.Unmarshal(topMetadataBytes, &topMetadata)
+	require.NoError(t, err)
+	assert.Equal(t, repoUrl, topMetadata.RepoURL)
+	assert.Equal(t, drySha, topMetadata.DrySHA)
+
+	for _, p := range paths {
+		fullHydratePath, err := securejoin.SecureJoin(dir, p.Path)
+		require.NoError(t, err)
+
+		// Check if each path directory exists
+		assert.DirExists(t, fullHydratePath)
+
+		// Check if each path contains a hydrator.metadata file and contains the repo URL
+		metadataPath := path.Join(fullHydratePath, "hydrator.metadata")
+		metadataBytes, err := os.ReadFile(metadataPath)
+		require.NoError(t, err)
+
+		var readMetadata hydratorMetadataFile
+		err = json.Unmarshal(metadataBytes, &readMetadata)
+		require.NoError(t, err)
+		assert.Equal(t, repoUrl, readMetadata.RepoURL)
+
+		// Check if each path contains a README.md file and contains the repo URL
+		readmePath := path.Join(fullHydratePath, "README.md")
+		readmeBytes, err := os.ReadFile(readmePath)
+		require.NoError(t, err)
+		assert.Contains(t, string(readmeBytes), repoUrl)
+
+		// Check if each path contains a manifest.yaml file and contains the word Pod
+		manifestPath := path.Join(fullHydratePath, "manifest.yaml")
+		manifestBytes, err := os.ReadFile(manifestPath)
+		require.NoError(t, err)
+		assert.Contains(t, string(manifestBytes), "kind")
+	}
+}
+
+func TestWriteMetadata(t *testing.T) {
+	dir := t.TempDir()
+
+	metadata := hydratorMetadataFile{
+		RepoURL: "https://github.com/example/repo",
+		DrySHA:  "abc123",
+	}
+
+	err := writeMetadata(dir, metadata)
+	require.NoError(t, err)
+
+	metadataPath := path.Join(dir, "hydrator.metadata")
+	metadataBytes, err := os.ReadFile(metadataPath)
+	require.NoError(t, err)
+
+	var readMetadata hydratorMetadataFile
+	err = json.Unmarshal(metadataBytes, &readMetadata)
+	require.NoError(t, err)
+	assert.Equal(t, metadata, readMetadata)
+}
+
+func TestWriteReadme(t *testing.T) {
+	dir := t.TempDir()
+
+	metadata := hydratorMetadataFile{
+		RepoURL: "https://github.com/example/repo",
+		DrySHA:  "abc123",
+	}
+
+	err := writeReadme(dir, metadata)
+	require.NoError(t, err)
+
+	readmePath := path.Join(dir, "README.md")
+	readmeBytes, err := os.ReadFile(readmePath)
+	require.NoError(t, err)
+	assert.Contains(t, string(readmeBytes), metadata.RepoURL)
+}
+
+func TestWriteManifests(t *testing.T) {
+	dir := t.TempDir()
+
+	manifests := []*apiclient.HydratedManifestDetails{
+		{ManifestJSON: `{"kind":"Pod","apiVersion":"v1"}`},
+	}
+
+	err := writeManifests(dir, manifests)
+	require.NoError(t, err)
+
+	manifestPath := path.Join(dir, "manifest.yaml")
+	manifestBytes, err := os.ReadFile(manifestPath)
+	require.NoError(t, err)
+	assert.Contains(t, string(manifestBytes), "kind")
+}

commitserver/commit/mocks/RepoClientFactory.go

@@ -0,0 +1,59 @@
+// Code generated by mockery v2.43.2. DO NOT EDIT.
+
+package mocks
+
+import (
+	git "github.com/argoproj/argo-cd/v2/util/git"
+	mock "github.com/stretchr/testify/mock"
+
+	v1alpha1 "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+)
+
+// RepoClientFactory is an autogenerated mock type for the RepoClientFactory type
+type RepoClientFactory struct {
+	mock.Mock
+}
+
+// NewClient provides a mock function with given fields: repo, rootPath
+func (_m *RepoClientFactory) NewClient(repo *v1alpha1.Repository, rootPath string) (git.Client, error) {
+	ret := _m.Called(repo, rootPath)
+
+	if len(ret) == 0 {
+		panic("no return value specified for NewClient")
+	}
+
+	var r0 git.Client
+	var r1 error
+	if rf, ok := ret.Get(0).(func(*v1alpha1.Repository, string) (git.Client, error)); ok {
+		return rf(repo, rootPath)
+	}
+	if rf, ok := ret.Get(0).(func(*v1alpha1.Repository, string) git.Client); ok {
+		r0 = rf(repo, rootPath)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(git.Client)
+		}
+	}
+
+	if rf, ok := ret.Get(1).(func(*v1alpha1.Repository, string) error); ok {
+		r1 = rf(repo, rootPath)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
+// NewRepoClientFactory creates a new instance of RepoClientFactory. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
+// The first argument is typically a *testing.T value.
+func NewRepoClientFactory(t interface {
+	mock.TestingT
+	Cleanup(func())
+}) *RepoClientFactory {
+	mock := &RepoClientFactory{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}

commitserver/commit/repo_client_factory.go

@@ -0,0 +1,32 @@
+package commit
+
+import (
+	"github.com/argoproj/argo-cd/v2/commitserver/metrics"
+	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+	"github.com/argoproj/argo-cd/v2/util/git"
+)
+
+// RepoClientFactory is a factory for creating git clients for a repository.
+type RepoClientFactory interface {
+	NewClient(repo *v1alpha1.Repository, rootPath string) (git.Client, error)
+}
+
+type repoClientFactory struct {
+	gitCredsStore git.CredsStore
+	metricsServer *metrics.Server
+}
+
+// NewRepoClientFactory returns a new instance of the repo client factory.
+func NewRepoClientFactory(gitCredsStore git.CredsStore, metricsServer *metrics.Server) RepoClientFactory {
+	return &repoClientFactory{
+		gitCredsStore: gitCredsStore,
+		metricsServer: metricsServer,
+	}
+}
+
+// NewClient creates a new git client for the repository.
+func (r *repoClientFactory) NewClient(repo *v1alpha1.Repository, rootPath string) (git.Client, error) {
+	gitCreds := repo.GetGitCreds(r.gitCredsStore)
+	opts := git.WithEventHandlers(metrics.NewGitClientEventHandlers(r.metricsServer))
+	return git.NewClientExt(repo.Repo, rootPath, gitCreds, repo.IsInsecure(), repo.IsLFSEnabled(), repo.Proxy, repo.NoProxy, opts)
+}

commitserver/metrics/githandlers.go

@@ -0,0 +1,34 @@
+package metrics
+
+import (
+	"time"
+
+	"github.com/argoproj/argo-cd/v2/util/git"
+)
+
+// NewGitClientEventHandlers creates event handlers that update Git related metrics
+func NewGitClientEventHandlers(metricsServer *Server) git.EventHandlers {
+	return git.EventHandlers{
+		OnFetch: func(repo string) func() {
+			startTime := time.Now()
+			metricsServer.IncGitRequest(repo, GitRequestTypeFetch)
+			return func() {
+				metricsServer.ObserveGitRequestDuration(repo, GitRequestTypeFetch, time.Since(startTime))
+			}
+		},
+		OnLsRemote: func(repo string) func() {
+			startTime := time.Now()
+			metricsServer.IncGitRequest(repo, GitRequestTypeLsRemote)
+			return func() {
+				metricsServer.ObserveGitRequestDuration(repo, GitRequestTypeLsRemote, time.Since(startTime))
+			}
+		},
+		OnPush: func(repo string) func() {
+			startTime := time.Now()
+			metricsServer.IncGitRequest(repo, GitRequestTypePush)
+			return func() {
+				metricsServer.ObserveGitRequestDuration(repo, GitRequestTypePush, time.Since(startTime))
+			}
+		},
+	}
+}

commitserver/metrics/metrics.go

@@ -0,0 +1,157 @@
+package metrics
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// Server is a prometheus server which collects application metrics.
+type Server struct {
+	handler                    http.Handler
+	commitPendingRequestsGauge *prometheus.GaugeVec
+	gitRequestCounter          *prometheus.CounterVec
+	gitRequestHistogram        *prometheus.HistogramVec
+	commitRequestHistogram     *prometheus.HistogramVec
+	userInfoRequestHistogram   *prometheus.HistogramVec
+	commitRequestCounter       *prometheus.CounterVec
+}
+
+// GitRequestType is the type of git request
+type GitRequestType string
+
+const (
+	// GitRequestTypeLsRemote is a request to list remote refs
+	GitRequestTypeLsRemote = "ls-remote"
+	// GitRequestTypeFetch is a request to fetch from remote
+	GitRequestTypeFetch = "fetch"
+	// GitRequestTypePush is a request to push to remote
+	GitRequestTypePush = "push"
+)
+
+// CommitResponseType is the type of response for a commit request
+type CommitResponseType string
+
+const (
+	// CommitResponseTypeSuccess is a successful commit request
+	CommitResponseTypeSuccess CommitResponseType = "success"
+	// CommitResponseTypeFailure is a failed commit request
+	CommitResponseTypeFailure CommitResponseType = "failure"
+)
+
+// NewMetricsServer returns a new prometheus server which collects application metrics.
+func NewMetricsServer() *Server {
+	registry := prometheus.NewRegistry()
+	registry.MustRegister(collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}))
+	registry.MustRegister(collectors.NewGoCollector())
+
+	commitPendingRequestsGauge := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "argocd_commitserver_commit_pending_request_total",
+			Help: "Number of pending commit requests",
+		},
+		[]string{"repo"},
+	)
+	registry.MustRegister(commitPendingRequestsGauge)
+
+	gitRequestCounter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "argocd_commitserver_git_request_total",
+			Help: "Number of git requests performed by repo server",
+		},
+		[]string{"repo", "request_type"},
+	)
+	registry.MustRegister(gitRequestCounter)
+
+	gitRequestHistogram := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "argocd_commitserver_git_request_duration_seconds",
+			Help:    "Git requests duration seconds.",
+			Buckets: []float64{0.1, 0.25, .5, 1, 2, 4, 10, 20},
+		},
+		[]string{"repo", "request_type"},
+	)
+	registry.MustRegister(gitRequestHistogram)
+
+	commitRequestHistogram := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "argocd_commitserver_commit_request_duration_seconds",
+			Help:    "Commit request duration seconds.",
+			Buckets: []float64{0.1, 0.25, .5, 1, 2, 4, 10, 20},
+		},
+		[]string{"repo", "response_type"},
+	)
+	registry.MustRegister(commitRequestHistogram)
+
+	userInfoRequestHistogram := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "argocd_commitserver_userinfo_request_duration_seconds",
+			Help:    "Userinfo request duration seconds.",
+			Buckets: []float64{0.1, 0.25, .5, 1, 2, 4, 10, 20},
+		},
+		[]string{"repo", "credential_type"},
+	)
+	registry.MustRegister(userInfoRequestHistogram)
+
+	commitRequestCounter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "argocd_commitserver_commit_request_total",
+			Help: "Number of commit requests performed handled",
+		},
+		[]string{"repo", "response_type"},
+	)
+	registry.MustRegister(commitRequestCounter)
+
+	return &Server{
+		handler:                    promhttp.HandlerFor(registry, promhttp.HandlerOpts{}),
+		commitPendingRequestsGauge: commitPendingRequestsGauge,
+		gitRequestCounter:          gitRequestCounter,
+		gitRequestHistogram:        gitRequestHistogram,
+		commitRequestHistogram:     commitRequestHistogram,
+		userInfoRequestHistogram:   userInfoRequestHistogram,
+		commitRequestCounter:       commitRequestCounter,
+	}
+}
+
+// GetHandler returns the http.Handler for the prometheus server
+func (m *Server) GetHandler() http.Handler {
+	return m.handler
+}
+
+// IncPendingCommitRequest increments the pending commit requests gauge
+func (m *Server) IncPendingCommitRequest(repo string) {
+	m.commitPendingRequestsGauge.WithLabelValues(repo).Inc()
+}
+
+// DecPendingCommitRequest decrements the pending commit requests gauge
+func (m *Server) DecPendingCommitRequest(repo string) {
+	m.commitPendingRequestsGauge.WithLabelValues(repo).Dec()
+}
+
+// IncGitRequest increments the git requests counter
+func (m *Server) IncGitRequest(repo string, requestType GitRequestType) {
+	m.gitRequestCounter.WithLabelValues(repo, string(requestType)).Inc()
+}
+
+// ObserveGitRequestDuration observes the duration of a git request
+func (m *Server) ObserveGitRequestDuration(repo string, requestType GitRequestType, duration time.Duration) {
+	m.gitRequestHistogram.WithLabelValues(repo, string(requestType)).Observe(duration.Seconds())
+}
+
+// ObserveCommitRequestDuration observes the duration of a commit request
+func (m *Server) ObserveCommitRequestDuration(repo string, rt CommitResponseType, duration time.Duration) {
+	m.commitRequestHistogram.WithLabelValues(repo, string(rt)).Observe(duration.Seconds())
+}
+
+// ObserveUserInfoRequestDuration observes the duration of a userinfo request
+func (m *Server) ObserveUserInfoRequestDuration(repo string, credentialType string, duration time.Duration) {
+	m.userInfoRequestHistogram.WithLabelValues(repo, credentialType).Observe(duration.Seconds())
+}
+
+// IncCommitRequest increments the commit request counter
+func (m *Server) IncCommitRequest(repo string, rt CommitResponseType) {
+	m.commitRequestCounter.WithLabelValues(repo, string(rt)).Inc()
+}

commitserver/server.go

@@ -0,0 +1,38 @@
+package commitserver
+
+import (
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/health"
+	"google.golang.org/grpc/health/grpc_health_v1"
+
+	"github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	"github.com/argoproj/argo-cd/v2/commitserver/commit"
+	"github.com/argoproj/argo-cd/v2/commitserver/metrics"
+	versionpkg "github.com/argoproj/argo-cd/v2/pkg/apiclient/version"
+	"github.com/argoproj/argo-cd/v2/server/version"
+	"github.com/argoproj/argo-cd/v2/util/git"
+)
+
+// ArgoCDCommitServer is the server that handles commit requests.
+type ArgoCDCommitServer struct {
+	commitService *commit.Service
+}
+
+// NewServer returns a new instance of the commit server.
+func NewServer(gitCredsStore git.CredsStore, metricsServer *metrics.Server) *ArgoCDCommitServer {
+	return &ArgoCDCommitServer{commitService: commit.NewService(gitCredsStore, metricsServer)}
+}
+
+// CreateGRPC creates a new gRPC server.
+func (a *ArgoCDCommitServer) CreateGRPC() *grpc.Server {
+	server := grpc.NewServer()
+	versionpkg.RegisterVersionServiceServer(server, version.NewServer(nil, func() (bool, error) {
+		return true, nil
+	}))
+	apiclient.RegisterCommitServiceServer(server, a.commitService)
+
+	healthService := health.NewServer()
+	grpc_health_v1.RegisterHealthServer(server, healthService)
+
+	return server
+}

common/common.go

@@ -26,6 +26,8 @@ const (
 const (
 	// DefaultRepoServerAddr is the gRPC address of the Argo CD repo server
 	DefaultRepoServerAddr = "argocd-repo-server:8081"
+	// DefaultCommitServerAddr is the gRPC address of the Argo CD commit server
+	DefaultCommitServerAddr = "argocd-commit-server:8086"
 	// DefaultDexServerAddr is the HTTP address of the Dex OIDC server, which we run a reverse proxy against
 	DefaultDexServerAddr = "argocd-dex-server:5556"
 	// DefaultRedisAddr is the default redis address
@@ -62,15 +64,19 @@ const (
 	DefaultPortArgoCDMetrics          = 8082
 	DefaultPortArgoCDAPIServerMetrics = 8083
 	DefaultPortRepoServerMetrics      = 8084
+	DefaultPortCommitServer           = 8086
+	DefaultPortCommitServerMetrics    = 8087
 )
 
 // DefaultAddressAPIServer for ArgoCD components
 const (
-	DefaultAddressAdminDashboard    = "localhost"
-	DefaultAddressAPIServer         = "0.0.0.0"
-	DefaultAddressAPIServerMetrics  = "0.0.0.0"
-	DefaultAddressRepoServer        = "0.0.0.0"
-	DefaultAddressRepoServerMetrics = "0.0.0.0"
+	DefaultAddressAdminDashboard      = "localhost"
+	DefaultAddressAPIServer           = "0.0.0.0"
+	DefaultAddressAPIServerMetrics    = "0.0.0.0"
+	DefaultAddressRepoServer          = "0.0.0.0"
+	DefaultAddressRepoServerMetrics   = "0.0.0.0"
+	DefaultAddressCommitServer        = "0.0.0.0"
+	DefaultAddressCommitServerMetrics = "0.0.0.0"
 )
 
 // Default paths on the pod's file system
@@ -175,6 +181,8 @@ const (
 	LabelValueSecretTypeRepository = "repository"
 	// LabelValueSecretTypeRepoCreds indicates a secret type of repository credentials
 	LabelValueSecretTypeRepoCreds = "repo-creds"
+	// LabelValueSecretTypeRepositoryWrite indicates a secret type of repository credentials for writing
+	LabelValueSecretTypeRepositoryWrite = "repository-write"
 	// LabelValueSecretTypeSCMCreds indicates a secret type of SCM credentials
 	LabelValueSecretTypeSCMCreds = "scm-creds"
 

controller/appcontroller.go

@@ -42,8 +42,10 @@ import (
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/client-go/util/workqueue"
 
+	commitclient "github.com/argoproj/argo-cd/v2/commitserver/apiclient"
 	"github.com/argoproj/argo-cd/v2/common"
 	statecache "github.com/argoproj/argo-cd/v2/controller/cache"
+	"github.com/argoproj/argo-cd/v2/controller/hydrator"
 	"github.com/argoproj/argo-cd/v2/controller/metrics"
 	"github.com/argoproj/argo-cd/v2/controller/sharding"
 	"github.com/argoproj/argo-cd/v2/pkg/apis/application"
@@ -121,6 +123,8 @@ type ApplicationController struct {
 	appComparisonTypeRefreshQueue workqueue.TypedRateLimitingInterface[string]
 	appOperationQueue             workqueue.TypedRateLimitingInterface[string]
 	projectRefreshQueue           workqueue.TypedRateLimitingInterface[string]
+	appHydrateQueue               workqueue.TypedRateLimitingInterface[string]
+	hydrationQueue                workqueue.TypedRateLimitingInterface[hydrator.HydrationQueueKey]
 	appInformer                   cache.SharedIndexInformer
 	appLister                     applisters.ApplicationLister
 	projInformer                  cache.SharedIndexInformer
@@ -146,6 +150,8 @@ type ApplicationController struct {
 	// dynamicClusterDistributionEnabled if disabled deploymentInformer is never initialized
 	dynamicClusterDistributionEnabled bool
 	deploymentInformer                informerv1.DeploymentInformer
+
+	hydrator *hydrator.Hydrator
 }
 
 // NewApplicationController creates new instance of ApplicationController.
@@ -155,6 +161,7 @@ func NewApplicationController(
 	kubeClientset kubernetes.Interface,
 	applicationClientset appclientset.Interface,
 	repoClientset apiclient.Clientset,
+	commitClientset commitclient.Clientset,
 	argoCache *appstatecache.Cache,
 	kubectl kube.Kubectl,
 	appResyncPeriod time.Duration,
@@ -177,6 +184,7 @@ func NewApplicationController(
 	dynamicClusterDistributionEnabled bool,
 	ignoreNormalizerOpts normalizers.IgnoreNormalizerOpts,
 	enableK8sEvent []string,
+	hydratorEnabled bool,
 ) (*ApplicationController, error) {
 	log.Infof("appResyncPeriod=%v, appHardResyncPeriod=%v, appResyncJitter=%v", appResyncPeriod, appHardResyncPeriod, appResyncJitter)
 	db := db.NewDB(namespace, settingsMgr, kubeClientset)
@@ -190,10 +198,12 @@ func NewApplicationController(
 		kubeClientset:                     kubeClientset,
 		kubectl:                           kubectl,
 		applicationClientset:              applicationClientset,
-		appRefreshQueue:                   workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter(rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "app_reconciliation_queue"}),
-		appOperationQueue:                 workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter(rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "app_operation_processing_queue"}),
-		projectRefreshQueue:               workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter(rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "project_reconciliation_queue"}),
-		appComparisonTypeRefreshQueue:     workqueue.NewTypedRateLimitingQueue(ratelimiter.NewCustomAppControllerRateLimiter(rateLimiterConfig)),
+		appRefreshQueue:                   workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter[string](rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "app_reconciliation_queue"}),
+		appOperationQueue:                 workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter[string](rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "app_operation_processing_queue"}),
+		projectRefreshQueue:               workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter[string](rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "project_reconciliation_queue"}),
+		appComparisonTypeRefreshQueue:     workqueue.NewTypedRateLimitingQueue(ratelimiter.NewCustomAppControllerRateLimiter[string](rateLimiterConfig)),
+		appHydrateQueue:                   workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter[string](rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[string]{Name: "app_hydration_queue"}),
+		hydrationQueue:                    workqueue.NewTypedRateLimitingQueueWithConfig(ratelimiter.NewCustomAppControllerRateLimiter[hydrator.HydrationQueueKey](rateLimiterConfig), workqueue.TypedRateLimitingQueueConfig[hydrator.HydrationQueueKey]{Name: "manifest_hydration_queue"}),
 		db:                                db,
 		statusRefreshTimeout:              appResyncPeriod,
 		statusHardRefreshTimeout:          appHardResyncPeriod,
@@ -211,6 +221,9 @@ func NewApplicationController(
 		dynamicClusterDistributionEnabled: dynamicClusterDistributionEnabled,
 		ignoreNormalizerOpts:              ignoreNormalizerOpts,
 	}
+	if hydratorEnabled {
+		ctrl.hydrator = hydrator.NewHydrator(&ctrl, appResyncPeriod, commitClientset)
+	}
 	if kubectlParallelismLimit > 0 {
 		ctrl.kubectlSemaphore = semaphore.NewWeighted(kubectlParallelismLimit)
 	}
@@ -845,6 +858,8 @@ func (ctrl *ApplicationController) Run(ctx context.Context, statusProcessors int
 	defer ctrl.appComparisonTypeRefreshQueue.ShutDown()
 	defer ctrl.appOperationQueue.ShutDown()
 	defer ctrl.projectRefreshQueue.ShutDown()
+	defer ctrl.appHydrateQueue.ShutDown()
+	defer ctrl.hydrationQueue.ShutDown()
 
 	ctrl.metricsServer.RegisterClustersInfoSource(ctx, ctrl.stateCache)
 	ctrl.RegisterClusterSecretUpdater(ctx)
@@ -903,6 +918,19 @@ func (ctrl *ApplicationController) Run(ctx context.Context, statusProcessors int
 		for ctrl.processProjectQueueItem() {
 		}
 	}, time.Second, ctx.Done())
+
+	if ctrl.hydrator != nil {
+		go wait.Until(func() {
+			for ctrl.processAppHydrateQueueItem() {
+			}
+		}, time.Second, ctx.Done())
+
+		go wait.Until(func() {
+			for ctrl.processHydrationQueueItem() {
+			}
+		}, time.Second, ctx.Done())
+	}
+
 	<-ctx.Done()
 }
 
@@ -1774,6 +1802,68 @@ func (ctrl *ApplicationController) processAppRefreshQueueItem() (processNext boo
 	return
 }
 
+func (ctrl *ApplicationController) processAppHydrateQueueItem() (processNext bool) {
+	appKey, shutdown := ctrl.appHydrateQueue.Get()
+	if shutdown {
+		processNext = false
+		return
+	}
+	processNext = true
+	defer func() {
+		if r := recover(); r != nil {
+			log.Errorf("Recovered from panic: %+v\n%s", r, debug.Stack())
+		}
+		ctrl.appHydrateQueue.Done(appKey)
+	}()
+	obj, exists, err := ctrl.appInformer.GetIndexer().GetByKey(appKey)
+	if err != nil {
+		log.Errorf("Failed to get application '%s' from informer index: %+v", appKey, err)
+		return
+	}
+	if !exists {
+		// This happens after app was deleted, but the work queue still had an entry for it.
+		return
+	}
+	origApp, ok := obj.(*appv1.Application)
+	if !ok {
+		log.Warnf("Key '%s' in index is not an application", appKey)
+		return
+	}
+
+	ctrl.hydrator.ProcessAppHydrateQueueItem(origApp)
+
+	getAppLog(origApp).Debug("Successfully processed app hydrate queue item")
+	return
+}
+
+func (ctrl *ApplicationController) processHydrationQueueItem() (processNext bool) {
+	hydrationKey, shutdown := ctrl.hydrationQueue.Get()
+	if shutdown {
+		processNext = false
+		return
+	}
+	processNext = true
+	defer func() {
+		if r := recover(); r != nil {
+			log.Errorf("Recovered from panic: %+v\n%s", r, debug.Stack())
+		}
+		ctrl.hydrationQueue.Done(hydrationKey)
+	}()
+
+	logCtx := log.WithFields(log.Fields{
+		"sourceRepoURL":        hydrationKey.SourceRepoURL,
+		"sourceTargetRevision": hydrationKey.SourceTargetRevision,
+		"destinationBranch":    hydrationKey.DestinationBranch,
+	})
+
+	logCtx.Debug("Processing hydration queue item")
+
+	ctrl.hydrator.ProcessHydrationQueueItem(hydrationKey)
+
+	logCtx.Debug("Successfully processed hydration queue item")
+	return
+}
+
 func resourceStatusKey(res appv1.ResourceStatus) string {
 	return strings.Join([]string{res.Group, res.Kind, res.Namespace, res.Name}, "/")
 }
@@ -1782,7 +1872,8 @@ func currentSourceEqualsSyncedSource(app *appv1.Application) bool {
 	if app.Spec.HasMultipleSources() {
 		return app.Spec.Sources.Equals(app.Status.Sync.ComparedTo.Sources)
 	}
-	return app.Spec.Source.Equals(&app.Status.Sync.ComparedTo.Source)
+	source := app.Spec.GetSource()
+	return source.Equals(&app.Status.Sync.ComparedTo.Source)
 }
 
 // needRefreshAppStatus answers if application status needs to be refreshed.
@@ -1918,6 +2009,7 @@ func (ctrl *ApplicationController) persistAppStatus(orig *appv1.Application, new
 			newAnnotations[k] = v
 		}
 		delete(newAnnotations, appv1.AnnotationKeyRefresh)
+		delete(newAnnotations, appv1.AnnotationKeyHydrate)
 	}
 	patch, modified, err := createMergePatch(
 		&appv1.Application{ObjectMeta: metav1.ObjectMeta{Annotations: orig.GetAnnotations()}, Status: orig.Status},
@@ -2325,6 +2417,9 @@ func (ctrl *ApplicationController) newApplicationInformerAndLister() (cache.Shar
 				if !newOK || (delay != nil && *delay != time.Duration(0)) {
 					ctrl.appOperationQueue.AddRateLimited(key)
 				}
+				if ctrl.hydrator != nil {
+					ctrl.appHydrateQueue.AddRateLimited(newApp.QualifiedName())
+				}
 				ctrl.clusterSharding.UpdateApp(newApp)
 			},
 			DeleteFunc: func(obj interface{}) {

controller/appcontroller_test.go

@@ -42,6 +42,7 @@ import (
 
 	dbmocks "github.com/argoproj/argo-cd/v2/util/db/mocks"
 
+	mockcommitclient "github.com/argoproj/argo-cd/v2/commitserver/apiclient/mocks"
 	mockstatecache "github.com/argoproj/argo-cd/v2/controller/cache/mocks"
 	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
 	appclientset "github.com/argoproj/argo-cd/v2/pkg/client/clientset/versioned/fake"
@@ -126,6 +127,8 @@ func newFakeControllerWithResync(data *fakeData, appResyncPeriod time.Duration,
 
 	mockRepoClientset := mockrepoclient.Clientset{RepoServerServiceClient: &mockRepoClient}
 
+	mockCommitClientset := mockcommitclient.Clientset{}
+
 	secret := corev1.Secret{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "argocd-secret",
@@ -157,6 +160,7 @@ func newFakeControllerWithResync(data *fakeData, appResyncPeriod time.Duration,
 		kubeClient,
 		appclientset.NewSimpleClientset(data.apps...),
 		&mockRepoClientset,
+		&mockCommitClientset,
 		appstatecache.NewCache(
 			cacheutil.NewCache(cacheutil.NewInMemoryCache(1*time.Minute)),
 			1*time.Minute,
@@ -182,6 +186,7 @@ func newFakeControllerWithResync(data *fakeData, appResyncPeriod time.Duration,
 		false,
 		normalizers.IgnoreNormalizerOpts{},
 		testEnableEventList,
+		false,
 	)
 	db := &dbmocks.ArgoDB{}
 	db.On("GetApplicationControllerReplicas").Return(1)

controller/hook.go

@@ -51,7 +51,7 @@ func (ctrl *ApplicationController) executePostDeleteHooks(app *v1alpha1.Applicat
 		revisions = append(revisions, src.TargetRevision)
 	}
 
-	targets, _, _, err := ctrl.appStateManager.GetRepoObjs(app, app.Spec.GetSources(), appLabelKey, revisions, false, false, false, proj, false)
+	targets, _, _, err := ctrl.appStateManager.GetRepoObjs(app, app.Spec.GetSources(), appLabelKey, revisions, false, false, false, proj, false, true)
 	if err != nil {
 		return false, err
 	}

controller/hydrator/hydrator.go

@@ -0,0 +1,362 @@
+package hydrator
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+
+	commitclient "github.com/argoproj/argo-cd/v2/commitserver/apiclient"
+	"github.com/argoproj/argo-cd/v2/controller/utils"
+	appv1 "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+	"github.com/argoproj/argo-cd/v2/reposerver/apiclient"
+	argoio "github.com/argoproj/argo-cd/v2/util/io"
+)
+
+// Dependencies is the interface for the dependencies of the Hydrator. It serves two purposes: 1) it prevents the
+// hydrator from having direct access to the app controller, and 2) it allows for easy mocking of dependencies in tests.
+// If you add something here, be sure that it is something the app controller needs to provide to the hydrator.
+type Dependencies interface {
+	// TODO: determine if we actually need to get the app, or if all the stuff we need the app for is done already on
+	//       the app controller side.
+	GetProcessableAppProj(app *appv1.Application) (*appv1.AppProject, error)
+	GetProcessableApps() (*appv1.ApplicationList, error)
+	GetRepoObjs(app *appv1.Application, source appv1.ApplicationSource, revision string, project *appv1.AppProject) ([]*unstructured.Unstructured, *apiclient.ManifestResponse, error)
+	GetWriteCredentials(ctx context.Context, repoURL string, project string) (*appv1.Repository, error)
+	ResolveGitRevision(repoURL, targetRevision string) (string, error)
+	RequestAppRefresh(appName string)
+	// TODO: only allow access to the hydrator status
+	PersistAppHydratorStatus(orig *appv1.Application, newStatus *appv1.SourceHydratorStatus)
+	AddHydrationQueueItem(key HydrationQueueKey)
+}
+
+type Hydrator struct {
+	dependencies         Dependencies
+	statusRefreshTimeout time.Duration
+	commitClientset      commitclient.Clientset
+}
+
+func NewHydrator(dependencies Dependencies, statusRefreshTimeout time.Duration, commitClientset commitclient.Clientset) *Hydrator {
+	return &Hydrator{
+		dependencies:         dependencies,
+		statusRefreshTimeout: statusRefreshTimeout,
+		commitClientset:      commitClientset,
+	}
+}
+
+func (h *Hydrator) ProcessAppHydrateQueueItem(origApp *appv1.Application) {
+	origApp = origApp.DeepCopy()
+	app := origApp.DeepCopy()
+
+	if app.Spec.SourceHydrator == nil {
+		return
+	}
+
+	logCtx := utils.GetAppLog(app)
+
+	logCtx.Debug("Processing app hydrate queue item")
+
+	// If we're using a source hydrator, see if the dry source has changed.
+	latestRevision, err := h.dependencies.ResolveGitRevision(app.Spec.SourceHydrator.DrySource.RepoURL, app.Spec.SourceHydrator.DrySource.TargetRevision)
+	if err != nil {
+		logCtx.Errorf("Failed to check whether dry source has changed, skipping: %v", err)
+		return
+	}
+
+	// TODO: don't reuse statusRefreshTimeout. Create a new timeout for hydration.
+	needsHydration, reason := appNeedsHydration(origApp, h.statusRefreshTimeout, latestRevision)
+	if !needsHydration {
+		return
+	}
+	if latestRevision == "" {
+		logCtx.Errorf("Dry source has not been resolved, skipping")
+		return
+	}
+
+	logCtx.WithField("reason", reason).Info("Hydrating app")
+
+	app.Status.SourceHydrator.CurrentOperation = &appv1.HydrateOperation{
+		DrySHA:         latestRevision,
+		StartedAt:      metav1.Now(),
+		FinishedAt:     nil,
+		Phase:          appv1.HydrateOperationPhaseHydrating,
+		SourceHydrator: *app.Spec.SourceHydrator,
+	}
+	h.dependencies.PersistAppHydratorStatus(origApp, &app.Status.SourceHydrator)
+	origApp.Status.SourceHydrator = app.Status.SourceHydrator
+	h.dependencies.AddHydrationQueueItem(getHydrationQueueKey(app))
+
+	logCtx.Debug("Successfully processed app hydrate queue item")
+}
+
+func getHydrationQueueKey(app *appv1.Application) HydrationQueueKey {
+	destinationBranch := app.Spec.SourceHydrator.SyncSource.TargetBranch
+	if app.Spec.SourceHydrator.HydrateTo != nil {
+		destinationBranch = app.Spec.SourceHydrator.HydrateTo.TargetBranch
+	}
+	key := HydrationQueueKey{
+		SourceRepoURL:        app.Spec.SourceHydrator.DrySource.RepoURL,
+		SourceTargetRevision: app.Spec.SourceHydrator.DrySource.TargetRevision,
+		DestinationBranch:    destinationBranch,
+	}
+	return key
+}
+
+type HydrationQueueKey struct {
+	SourceRepoURL        string
+	SourceTargetRevision string
+	DestinationBranch    string
+}
+
+// uniqueHydrationDestination is used to detect duplicate hydrate destinations.
+type uniqueHydrationDestination struct {
+	sourceRepoURL        string
+	sourceTargetRevision string
+	destinationBranch    string
+	destinationPath      string
+}
+
+func (h *Hydrator) ProcessHydrationQueueItem(hydrationKey HydrationQueueKey) (processNext bool) {
+	logCtx := log.WithFields(log.Fields{
+		"sourceRepoURL":        hydrationKey.SourceRepoURL,
+		"sourceTargetRevision": hydrationKey.SourceTargetRevision,
+		"destinationBranch":    hydrationKey.DestinationBranch,
+	})
+
+	relevantApps, drySHA, hydratedSHA, err := h.hydrateAppsLatestCommit(logCtx, hydrationKey)
+	if drySHA != "" {
+		logCtx = logCtx.WithField("drySHA", drySHA)
+	}
+	if err != nil {
+		logCtx.WithField("appCount", len(relevantApps)).WithError(err).Error("Failed to hydrate apps")
+		for _, app := range relevantApps {
+			origApp := app.DeepCopy()
+			app.Status.SourceHydrator.CurrentOperation.Phase = appv1.HydrateOperationPhaseFailed
+			failedAt := metav1.Now()
+			app.Status.SourceHydrator.CurrentOperation.FinishedAt = &failedAt
+			app.Status.SourceHydrator.CurrentOperation.Message = fmt.Sprintf("Failed to hydrated revision %s: %v", drySHA, err.Error())
+			h.dependencies.PersistAppHydratorStatus(origApp, &app.Status.SourceHydrator)
+			logCtx = logCtx.WithField("app", app.QualifiedName())
+			logCtx.Errorf("Failed to hydrate app: %v", err)
+		}
+		return
+	}
+	logCtx.WithField("appCount", len(relevantApps)).Debug("Successfully hydrated apps")
+	finishedAt := metav1.Now()
+	for _, app := range relevantApps {
+		origApp := app.DeepCopy()
+		operation := &appv1.HydrateOperation{
+			StartedAt:      app.Status.SourceHydrator.CurrentOperation.StartedAt,
+			FinishedAt:     &finishedAt,
+			Phase:          appv1.HydrateOperationPhaseHydrated,
+			Message:        "",
+			DrySHA:         drySHA,
+			HydratedSHA:    hydratedSHA,
+			SourceHydrator: app.Status.SourceHydrator.CurrentOperation.SourceHydrator,
+		}
+		app.Status.SourceHydrator.CurrentOperation = operation
+		app.Status.SourceHydrator.LastSuccessfulOperation = &appv1.SuccessfulHydrateOperation{
+			DrySHA:         drySHA,
+			HydratedSHA:    hydratedSHA,
+			SourceHydrator: app.Status.SourceHydrator.CurrentOperation.SourceHydrator,
+		}
+		h.dependencies.PersistAppHydratorStatus(origApp, &app.Status.SourceHydrator)
+		// Request a refresh since we pushed a new commit.
+		h.dependencies.RequestAppRefresh(app.QualifiedName())
+	}
+	return
+}
+
+func (h *Hydrator) hydrateAppsLatestCommit(logCtx *log.Entry, hydrationKey HydrationQueueKey) ([]*appv1.Application, string, string, error) {
+	relevantApps, err := h.getRelevantAppsForHydration(logCtx, hydrationKey)
+	if err != nil {
+		return nil, "", "", fmt.Errorf("failed to get relevant apps for hydration: %w", err)
+	}
+
+	dryRevision, err := h.dependencies.ResolveGitRevision(hydrationKey.SourceRepoURL, hydrationKey.SourceTargetRevision)
+	if err != nil {
+		return relevantApps, "", "", fmt.Errorf("failed to resolve dry revision: %w", err)
+	}
+
+	hydratedRevision, err := h.hydrate(logCtx, relevantApps, dryRevision)
+	if err != nil {
+		return relevantApps, dryRevision, "", fmt.Errorf("failed to hydrate apps: %w", err)
+	}
+
+	return relevantApps, dryRevision, hydratedRevision, nil
+}
+
+func (h *Hydrator) getRelevantAppsForHydration(logCtx *log.Entry, hydrationKey HydrationQueueKey) ([]*appv1.Application, error) {
+	// Get all apps
+	apps, err := h.dependencies.GetProcessableApps()
+	if err != nil {
+		return nil, fmt.Errorf("failed to list apps: %w", err)
+	}
+
+	var relevantApps []*appv1.Application
+	uniqueDestinations := make(map[uniqueHydrationDestination]bool, len(apps.Items))
+	for _, app := range apps.Items {
+		if app.Spec.SourceHydrator == nil {
+			continue
+		}
+
+		if app.Spec.SourceHydrator.DrySource.RepoURL != hydrationKey.SourceRepoURL ||
+			app.Spec.SourceHydrator.DrySource.TargetRevision != hydrationKey.SourceTargetRevision {
+			continue
+		}
+		destinationBranch := app.Spec.SourceHydrator.SyncSource.TargetBranch
+		if app.Spec.SourceHydrator.HydrateTo != nil {
+			destinationBranch = app.Spec.SourceHydrator.HydrateTo.TargetBranch
+		}
+		if destinationBranch != hydrationKey.DestinationBranch {
+			continue
+		}
+
+		var proj *appv1.AppProject
+		proj, err = h.dependencies.GetProcessableAppProj(&app)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get project %q for app %q: %w", app.Spec.Project, app.QualifiedName(), err)
+		}
+		permitted := proj.IsSourcePermitted(app.Spec.GetSource())
+		if !permitted {
+			// Log and skip. We don't want to fail the entire operation because of one app.
+			logCtx.Warnf("App %q is not permitted to use source %q", app.QualifiedName(), app.Spec.Source.String())
+			continue
+		}
+
+		uniqueDestinationKey := uniqueHydrationDestination{
+			sourceRepoURL:        app.Spec.SourceHydrator.DrySource.RepoURL,
+			sourceTargetRevision: app.Spec.SourceHydrator.DrySource.TargetRevision,
+			destinationBranch:    destinationBranch,
+			destinationPath:      app.Spec.SourceHydrator.SyncSource.Path,
+		}
+		// TODO: test the dupe detection
+		if _, ok := uniqueDestinations[uniqueDestinationKey]; ok {
+			return nil, fmt.Errorf("multiple app hydrators use the same destination: %v", uniqueDestinationKey)
+		}
+		uniqueDestinations[uniqueDestinationKey] = true
+
+		relevantApps = append(relevantApps, &app)
+	}
+	return relevantApps, nil
+}
+
+func (h *Hydrator) hydrate(logCtx *log.Entry, apps []*appv1.Application, revision string) (string, error) {
+	if len(apps) == 0 {
+		return "", nil
+	}
+	repoURL := apps[0].Spec.SourceHydrator.DrySource.RepoURL
+	syncBranch := apps[0].Spec.SourceHydrator.SyncSource.TargetBranch
+	targetBranch := apps[0].Spec.GetHydrateToSource().TargetRevision
+	var paths []*commitclient.PathDetails
+	projects := make(map[string]bool, len(apps))
+	// TODO: parallelize this loop
+	for _, app := range apps {
+		project, err := h.dependencies.GetProcessableAppProj(app)
+		if err != nil {
+			return "", fmt.Errorf("failed to get project: %w", err)
+		}
+		projects[project.Name] = true
+		drySource := appv1.ApplicationSource{
+			RepoURL:        app.Spec.SourceHydrator.DrySource.RepoURL,
+			Path:           app.Spec.SourceHydrator.DrySource.Path,
+			TargetRevision: app.Spec.SourceHydrator.DrySource.TargetRevision,
+		}
+		targetRevision := app.Spec.SourceHydrator.DrySource.TargetRevision
+
+		// TODO: enable signature verification
+		objs, resp, err := h.dependencies.GetRepoObjs(app, drySource, targetRevision, project)
+		if err != nil {
+			return "", fmt.Errorf("failed to get repo objects: %w", err)
+		}
+
+		// Set up a ManifestsRequest
+		manifestDetails := make([]*commitclient.HydratedManifestDetails, len(objs))
+		for i, obj := range objs {
+			objJson, err := json.Marshal(obj)
+			if err != nil {
+				return "", fmt.Errorf("failed to marshal object: %w", err)
+			}
+			manifestDetails[i] = &commitclient.HydratedManifestDetails{ManifestJSON: string(objJson)}
+		}
+
+		paths = append(paths, &commitclient.PathDetails{
+			Path:      app.Spec.SourceHydrator.SyncSource.Path,
+			Manifests: manifestDetails,
+			Commands:  resp.Commands,
+		})
+	}
+
+	// If all the apps are under the same project, use that project. Otherwise, use an empty string to indicate that we
+	// need global creds.
+	project := ""
+	if len(projects) == 1 {
+		for p := range projects {
+			project = p
+		}
+	}
+
+	repo, err := h.dependencies.GetWriteCredentials(context.Background(), repoURL, project)
+	if err != nil {
+		return "", fmt.Errorf("failed to get hydrator credentials: %w", err)
+	}
+	if repo == nil {
+		// Try without credentials.
+		repo = &appv1.Repository{
+			Repo: repoURL,
+		}
+		logCtx.Warn("no credentials found for repo, continuing without credentials")
+	}
+
+	manifestsRequest := commitclient.CommitHydratedManifestsRequest{
+		Repo:          repo,
+		SyncBranch:    syncBranch,
+		TargetBranch:  targetBranch,
+		DrySha:        revision,
+		CommitMessage: fmt.Sprintf("[Argo CD Bot] hydrate %s", revision),
+		Paths:         paths,
+	}
+
+	closer, commitService, err := h.commitClientset.NewCommitServerClient()
+	if err != nil {
+		return "", fmt.Errorf("failed to create commit service: %w", err)
+	}
+	defer argoio.Close(closer)
+	resp, err := commitService.CommitHydratedManifests(context.Background(), &manifestsRequest)
+	if err != nil {
+		return "", fmt.Errorf("failed to commit hydrated manifests: %w", err)
+	}
+	return resp.HydratedSha, nil
+}
+
+// appNeedsHydration answers if application needs manifests hydrated.
+func appNeedsHydration(app *appv1.Application, statusHydrateTimeout time.Duration, latestRevision string) (needsHydration bool, reason string) {
+	if app.Spec.SourceHydrator == nil {
+		return false, "source hydrator not configured"
+	}
+
+	var hydratedAt *metav1.Time
+	if app.Status.SourceHydrator.CurrentOperation != nil {
+		hydratedAt = &app.Status.SourceHydrator.CurrentOperation.StartedAt
+	}
+
+	if app.IsHydrateRequested() {
+		return true, "hydrate requested"
+	} else if app.Status.SourceHydrator.CurrentOperation == nil {
+		return true, "no previous hydrate operation"
+	} else if !app.Spec.SourceHydrator.DeepEquals(app.Status.SourceHydrator.CurrentOperation.SourceHydrator) {
+		return true, "spec.sourceHydrator differs"
+	} else if app.Status.SourceHydrator.CurrentOperation.DrySHA != latestRevision {
+		return true, "revision differs"
+	} else if app.Status.SourceHydrator.CurrentOperation.Phase == appv1.HydrateOperationPhaseFailed && metav1.Now().Sub(app.Status.SourceHydrator.CurrentOperation.FinishedAt.Time) > 2*time.Minute {
+		return true, "previous hydrate operation failed more than 2 minutes ago"
+	} else if hydratedAt == nil || hydratedAt.Add(statusHydrateTimeout).Before(time.Now().UTC()) {
+		return true, "hydration expired"
+	}
+
+	return false, ""
+}

controller/hydrator/hydrator_test.go

@@ -0,0 +1,114 @@
+package hydrator
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+)
+
+func Test_appNeedsHydration(t *testing.T) {
+	t.Parallel()
+
+	now := metav1.NewTime(time.Now())
+	oneHourAgo := metav1.NewTime(now.Add(-1 * time.Hour))
+
+	testCases := []struct {
+		name           string
+		app            *v1alpha1.Application
+		timeout        time.Duration
+		latestRevision string
+		expected       string
+	}{
+		{
+			name:     "source hydrator not configured",
+			app:      &v1alpha1.Application{},
+			expected: "source hydrator not configured",
+		},
+		{
+			name: "hydrate requested",
+			app: &v1alpha1.Application{
+				ObjectMeta: metav1.ObjectMeta{Annotations: map[string]string{v1alpha1.AnnotationKeyHydrate: "normal"}},
+				Spec:       v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+			},
+			timeout:        1 * time.Hour,
+			latestRevision: "abc123",
+			expected:       "hydrate requested",
+		},
+		{
+			name: "no previous hydrate operation",
+			app: &v1alpha1.Application{
+				Spec: v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+			},
+			timeout:        1 * time.Hour,
+			latestRevision: "abc123",
+			expected:       "no previous hydrate operation",
+		},
+		{
+			name: "spec.sourceHydrator differs",
+			app: &v1alpha1.Application{
+				Spec: v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+				Status: v1alpha1.ApplicationStatus{SourceHydrator: v1alpha1.SourceHydratorStatus{CurrentOperation: &v1alpha1.HydrateOperation{
+					SourceHydrator: v1alpha1.SourceHydrator{DrySource: v1alpha1.DrySource{RepoURL: "something new"}},
+				}}},
+			},
+			timeout:        1 * time.Hour,
+			latestRevision: "abc123",
+			expected:       "spec.sourceHydrator differs",
+		},
+		{
+			name: "dry SHA has changed",
+			app: &v1alpha1.Application{
+				Spec:   v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+				Status: v1alpha1.ApplicationStatus{SourceHydrator: v1alpha1.SourceHydratorStatus{CurrentOperation: &v1alpha1.HydrateOperation{DrySHA: "xyz123"}}},
+			},
+			timeout:        1 * time.Hour,
+			latestRevision: "abc123",
+			expected:       "revision differs",
+		},
+		{
+			name: "hydration failed more than two minutes ago",
+			app: &v1alpha1.Application{
+				Spec:   v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+				Status: v1alpha1.ApplicationStatus{SourceHydrator: v1alpha1.SourceHydratorStatus{CurrentOperation: &v1alpha1.HydrateOperation{DrySHA: "abc123", FinishedAt: &oneHourAgo, Phase: v1alpha1.HydrateOperationPhaseFailed}}},
+			},
+			timeout:        1 * time.Hour,
+			latestRevision: "abc123",
+			expected:       "previous hydrate operation failed more than 2 minutes ago",
+		},
+		{
+			name: "timeout reached",
+			app: &v1alpha1.Application{
+				Spec:   v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+				Status: v1alpha1.ApplicationStatus{SourceHydrator: v1alpha1.SourceHydratorStatus{CurrentOperation: &v1alpha1.HydrateOperation{StartedAt: oneHourAgo}}},
+			},
+			timeout:        1 * time.Minute,
+			latestRevision: "",
+			expected:       "hydration expired",
+		},
+		{
+			name: "hydrate not needed",
+			app: &v1alpha1.Application{
+				Spec:   v1alpha1.ApplicationSpec{SourceHydrator: &v1alpha1.SourceHydrator{}},
+				Status: v1alpha1.ApplicationStatus{SourceHydrator: v1alpha1.SourceHydratorStatus{CurrentOperation: &v1alpha1.HydrateOperation{DrySHA: "abc123", StartedAt: now, FinishedAt: &now, Phase: v1alpha1.HydrateOperationPhaseFailed}}},
+			},
+			timeout:        1 * time.Hour,
+			latestRevision: "abc123",
+			expected:       "",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			needsHydration, result := appNeedsHydration(tc.app, tc.timeout, tc.latestRevision)
+			assert.Equal(t, tc.expected, result)
+			if !needsHydration {
+				assert.Empty(t, result)
+			}
+		})
+	}
+}

controller/hydrator_dependencies.go

@@ -0,0 +1,75 @@
+package controller
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/argoproj/argo-cd/v2/controller/hydrator"
+	appv1 "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+	"github.com/argoproj/argo-cd/v2/reposerver/apiclient"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+)
+
+/**
+This file implements the hydrator.Dependencies interface for the ApplicationController.
+
+Hydration logic does not belong in this file. The methods here should be "bookkeeping" methods that keep hydration work
+in the hydrator and app controller work in the app controller. The only purpose of this file is to provide the hydrator
+safe, minimal access to certain app controller functionality to avoid duplicate code.
+*/
+
+func (ctrl *ApplicationController) GetProcessableAppProj(app *appv1.Application) (*appv1.AppProject, error) {
+	return ctrl.getAppProj(app)
+}
+
+// GetProcessableApps returns a list of applications that are processable by the controller.
+func (ctrl *ApplicationController) GetProcessableApps() (*appv1.ApplicationList, error) {
+	// getAppList already filters out applications that are not processable by the controller.
+	return ctrl.getAppList(metav1.ListOptions{})
+}
+
+func (ctrl *ApplicationController) GetRepoObjs(app *appv1.Application, source appv1.ApplicationSource, revision string, project *appv1.AppProject) ([]*unstructured.Unstructured, *apiclient.ManifestResponse, error) {
+	sources := []appv1.ApplicationSource{source}
+	revisions := []string{revision}
+
+	appLabelKey, err := ctrl.settingsMgr.GetAppInstanceLabelKey()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to get app instance label key: %w", err)
+	}
+
+	// FIXME: use cache and revision cache
+	objs, resp, _, err := ctrl.appStateManager.GetRepoObjs(app, sources, appLabelKey, revisions, true, true, false, project, false, false)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to get repo objects: %w", err)
+	}
+
+	if len(resp) != 1 {
+		return nil, nil, fmt.Errorf("expected one manifest response, got %d", len(resp))
+	}
+
+	return objs, resp[0], nil
+}
+
+func (ctrl *ApplicationController) GetWriteCredentials(ctx context.Context, repoURL string, project string) (*appv1.Repository, error) {
+	return ctrl.db.GetWriteRepository(ctx, repoURL, project)
+}
+
+func (ctrl *ApplicationController) ResolveGitRevision(repoURL, targetRevision string) (string, error) {
+	return ctrl.appStateManager.ResolveGitRevision(repoURL, targetRevision)
+}
+
+func (ctrl *ApplicationController) RequestAppRefresh(appName string) {
+	ctrl.requestAppRefresh(appName, CompareWithLatest.Pointer(), nil)
+}
+
+func (ctrl *ApplicationController) PersistAppHydratorStatus(orig *appv1.Application, newStatus *appv1.SourceHydratorStatus) {
+	status := orig.Status.DeepCopy()
+	status.SourceHydrator = *newStatus
+	ctrl.persistAppStatus(orig, status)
+}
+
+func (ctrl *ApplicationController) AddHydrationQueueItem(key hydrator.HydrationQueueKey) {
+	ctrl.hydrationQueue.AddRateLimited(key)
+}

controller/log_utils.go

@@ -0,0 +1 @@
+package controller

controller/state.go

@@ -71,7 +71,8 @@ type managedResource struct {
 type AppStateManager interface {
 	CompareAppState(app *v1alpha1.Application, project *v1alpha1.AppProject, revisions []string, sources []v1alpha1.ApplicationSource, noCache bool, noRevisionCache bool, localObjects []string, hasMultipleSources bool, rollback bool) (*comparisonResult, error)
 	SyncAppState(app *v1alpha1.Application, state *v1alpha1.OperationState)
-	GetRepoObjs(app *v1alpha1.Application, sources []v1alpha1.ApplicationSource, appLabelKey string, revisions []string, noCache, noRevisionCache, verifySignature bool, proj *v1alpha1.AppProject, rollback bool) ([]*unstructured.Unstructured, []*apiclient.ManifestResponse, bool, error)
+	GetRepoObjs(app *v1alpha1.Application, sources []v1alpha1.ApplicationSource, appLabelKey string, revisions []string, noCache, noRevisionCache, verifySignature bool, proj *v1alpha1.AppProject, rollback, sendRuntimeState bool) ([]*unstructured.Unstructured, []*apiclient.ManifestResponse, bool, error)
+	ResolveGitRevision(repoURL string, revision string) (string, error)
 }
 
 // comparisonResult holds the state of an application after the reconciliation
@@ -125,7 +126,7 @@ type appStateManager struct {
 // task to the repo-server. It returns the list of generated manifests as unstructured
 // objects. It also returns the full response from all calls to the repo server as the
 // second argument.
-func (m *appStateManager) GetRepoObjs(app *v1alpha1.Application, sources []v1alpha1.ApplicationSource, appLabelKey string, revisions []string, noCache, noRevisionCache, verifySignature bool, proj *v1alpha1.AppProject, rollback bool) ([]*unstructured.Unstructured, []*apiclient.ManifestResponse, bool, error) {
+func (m *appStateManager) GetRepoObjs(app *v1alpha1.Application, sources []v1alpha1.ApplicationSource, appLabelKey string, revisions []string, noCache, noRevisionCache, verifySignature bool, proj *v1alpha1.AppProject, rollback, sendRuntimeState bool) ([]*unstructured.Unstructured, []*apiclient.ManifestResponse, bool, error) {
 	ts := stats.NewTimingStats()
 	helmRepos, err := m.db.ListHelmRepositories(context.Background())
 	if err != nil {
@@ -219,6 +220,14 @@ func (m *appStateManager) GetRepoObjs(app *v1alpha1.Application, sources []v1alp
 
 		revision := revisions[i]
 
+		appNamespace := app.Spec.Destination.Namespace
+		apiVersions := argo.APIResourcesToStrings(apiResources, true)
+		if !sendRuntimeState {
+			appNamespace = ""
+			apiVersions = nil
+			serverVersion = ""
+		}
+
 		if !source.IsHelm() && syncedRevision != "" && keyManifestGenerateAnnotationExists && keyManifestGenerateAnnotationVal != "" {
 			// Validate the manifest-generate-path annotation to avoid generating manifests if it has not changed.
 			updateRevisionResult, err := repoClient.UpdateRevisionForPaths(context.Background(), &apiclient.UpdateRevisionForPathsRequest{
@@ -229,10 +238,10 @@ func (m *appStateManager) GetRepoObjs(app *v1alpha1.Application, sources []v1alp
 				Paths:              path.GetAppRefreshPaths(app),
 				AppLabelKey:        appLabelKey,
 				AppName:            app.InstanceName(m.namespace),
-				Namespace:          app.Spec.Destination.Namespace,
+				Namespace:          appNamespace,
 				ApplicationSource:  &source,
 				KubeVersion:        serverVersion,
-				ApiVersions:        argo.APIResourcesToStrings(apiResources, true),
+				ApiVersions:        apiVersions,
 				TrackingMethod:     string(argo.GetTrackingMethod(m.settingsMgr)),
 				RefSources:         refSources,
 				HasMultipleSources: app.Spec.HasMultipleSources(),
@@ -263,11 +272,11 @@ func (m *appStateManager) GetRepoObjs(app *v1alpha1.Application, sources []v1alp
 			NoRevisionCache:                 noRevisionCache,
 			AppLabelKey:                     appLabelKey,
 			AppName:                         app.InstanceName(m.namespace),
-			Namespace:                       app.Spec.Destination.Namespace,
+			Namespace:                       appNamespace,
 			ApplicationSource:               &source,
 			KustomizeOptions:                kustomizeOptions,
 			KubeVersion:                     serverVersion,
-			ApiVersions:                     argo.APIResourcesToStrings(apiResources, true),
+			ApiVersions:                     apiVersions,
 			VerifySignature:                 verifySignature,
 			HelmRepoCreds:                   permittedHelmCredentials,
 			TrackingMethod:                  string(argo.GetTrackingMethod(m.settingsMgr)),
@@ -309,6 +318,39 @@ func (m *appStateManager) GetRepoObjs(app *v1alpha1.Application, sources []v1alp
 	return targetObjs, manifestInfos, revisionUpdated, nil
 }
 
+// ResolveGitRevision will resolve the given revision to a full commit SHA. Only works for git.
+func (m *appStateManager) ResolveGitRevision(repoURL string, revision string) (string, error) {
+	conn, repoClient, err := m.repoClientset.NewRepoServerClient()
+	if err != nil {
+		return "", fmt.Errorf("failed to connect to repo server: %w", err)
+	}
+	defer io.Close(conn)
+
+	repo, err := m.db.GetRepository(context.Background(), repoURL, "")
+	if err != nil {
+		return "", fmt.Errorf("failed to get repo %q: %w", repoURL, err)
+	}
+
+	// Mock the app. The repo-server only needs to know whether the "chart" field is populated.
+	app := &v1alpha1.Application{
+		Spec: v1alpha1.ApplicationSpec{
+			Source: &v1alpha1.ApplicationSource{
+				RepoURL:        repoURL,
+				TargetRevision: revision,
+			},
+		},
+	}
+	resp, err := repoClient.ResolveRevision(context.Background(), &apiclient.ResolveRevisionRequest{
+		Repo:              repo,
+		App:               app,
+		AmbiguousRevision: revision,
+	})
+	if err != nil {
+		return "", fmt.Errorf("failed to determine whether the dry source has changed: %w", err)
+	}
+	return resp.Revision, nil
+}
+
 func unmarshalManifests(manifests []string) ([]*unstructured.Unstructured, error) {
 	targetObjs := make([]*unstructured.Unstructured, 0)
 	for _, manifest := range manifests {
@@ -490,7 +532,7 @@ func (m *appStateManager) CompareAppState(app *v1alpha1.Application, project *v1
 			}
 		}
 
-		targetObjs, manifestInfos, revisionUpdated, err = m.GetRepoObjs(app, sources, appLabelKey, revisions, noCache, noRevisionCache, verifySignature, project, rollback)
+		targetObjs, manifestInfos, revisionUpdated, err = m.GetRepoObjs(app, sources, appLabelKey, revisions, noCache, noRevisionCache, verifySignature, project, rollback, true)
 		if err != nil {
 			targetObjs = make([]*unstructured.Unstructured, 0)
 			msg := fmt.Sprintf("Failed to load target state: %s", err.Error())

controller/sync_test.go

@@ -56,7 +56,7 @@ func TestPersistRevisionHistory(t *testing.T) {
 
 	updatedApp, err := ctrl.applicationClientset.ArgoprojV1alpha1().Applications(app.Namespace).Get(context.Background(), app.Name, v1.GetOptions{})
 	require.NoError(t, err)
-	assert.Len(t, updatedApp.Status.History, 1)
+	require.Len(t, updatedApp.Status.History, 1)
 	assert.Equal(t, app.Spec.GetSource(), updatedApp.Status.History[0].Source)
 	assert.Equal(t, "abc123", updatedApp.Status.History[0].Revision)
 }

controller/utils/log.go

@@ -0,0 +1,17 @@
+package utils
+
+import (
+	"github.com/sirupsen/logrus"
+
+	"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+)
+
+// GetAppLog returns a logrus entry with fields set for the given application.
+func GetAppLog(app *v1alpha1.Application) *logrus.Entry {
+	return logrus.WithFields(logrus.Fields{
+		"application":        app.Name,
+		"app-namespace":      app.Namespace,
+		"app-qualified-name": app.QualifiedName(),
+		"project":            app.Spec.Project,
+	})
+}

docs/operator-manual/argocd-cmd-params-cm.yaml

@@ -9,6 +9,9 @@ data:
   # Repo server address. (default "argocd-repo-server:8081")
   repo.server: "argocd-repo-server:8081"
 
+  # Commit server address. (default "argocd-commit-server:8086")
+  commit.server: "argocd-commit-server:8086"
+
   # Redis server hostname and port (e.g. argocd-redis:6379)
   redis.server: "argocd-redis:6379"
   # Enable compression for data sent to Redis with the required compression algorithm. (default 'gzip')
@@ -16,6 +19,9 @@ data:
   # Redis database
   redis.db:
 
+  # Enables the alpha "manifest hydrator" feature. (default "false")
+  hydrator.enabled: "false"
+
   # Open-Telemetry collector address: (e.g. "otel-collector:4317")
   otlp.address: ""
   # Open-Telemetry collector insecure: (e.g. "true")
@@ -195,6 +201,15 @@ data:
   # Include hidden directories from Git
   reposerver.include.hidden.directories: "false"
 
+  ## Commit-server properties
+  # Listen on given address for incoming connections (default "0.0.0.0")
+  commitserver.listen.address: "0.0.0.0"
+  # Set the logging format. One of: text|json (default "text")
+  commitserver.log.format: "text"
+  # Set the logging level. One of: debug|info|warn|error (default "info")
+  commitserver.log.level: "info"
+  # Listen on given address for metrics (default "0.0.0.0")
+  commitserver.metrics.listen.address: "0.0.0.0"
 
   # Set the logging format. One of: text|json (default "text")
   dexserver.log.format: "text"

docs/operator-manual/metrics.md

@@ -129,6 +129,20 @@ Scraped at the `argocd-repo-server:8084/metrics` endpoint.
 | `argocd_redis_request_total` | counter | Number of Kubernetes requests executed during application reconciliation. |
 | `argocd_repo_pending_request_total` | gauge | Number of pending requests requiring repository lock |
 
+## Commit Server Metrics
+
+Metrics about the Commit Server.
+Scraped at the `argocd-commit-server:8087/metrics` endpoint.
+
+| Metric                                                  |   Type    | Description                                          |
+|---------------------------------------------------------|:---------:|------------------------------------------------------|
+| `argocd_commitserver_commit_pending_request_total`      |   guage   | Number of pending commit requests.                   |
+| `argocd_commitserver_git_request_duration_seconds`      | histogram | Git requests duration seconds.                       |
+| `argocd_commitserver_git_request_total`                 |  counter  | Number of git requests performed by commit server    |
+| `argocd_commitserver_commit_request_duration_seconds`   | histogram | Commit requests duration seconds.                    |
+| `argocd_commitserver_userinfo_request_duration_seconds` | histogram | Userinfo requests duration seconds.                  |
+| `argocd_commitserver_commit_request_total`              |  counter  | Number of commit requests performed by commit server |
+
 ## Prometheus Operator
 
 If using Prometheus Operator, the following ServiceMonitor example manifests can be used.

docs/operator-manual/server-commands/argocd-application-controller.md

@@ -27,6 +27,7 @@ argocd-application-controller [flags]
       --client-certificate string                                 Path to a client certificate file for TLS
       --client-key string                                         Path to a client key file for TLS
       --cluster string                                            The name of the kubeconfig cluster to use
+      --commit-server string                                      Commit server address. (default "argocd-commit-server:8086")
       --context string                                            The name of the kubeconfig context to use
       --default-cache-expiration duration                         Cache expiration default (default 24h0m0s)
       --disable-compression                                       If true, opt-out of response compression for all requests to the server
@@ -34,6 +35,7 @@ argocd-application-controller [flags]
       --enable-k8s-event none                                     Enable ArgoCD to use k8s event. For disabling all events, set the value as none. (e.g --enable-k8s-event=none), For enabling specific events, set the value as `event reason`. (e.g --enable-k8s-event=StatusRefreshed,ResourceCreated) (default [all])
       --gloglevel int                                             Set the glog logging level
   -h, --help                                                      help for argocd-application-controller
+      --hydrator-enabled                                          Feature flag to enable Hydrator. Default ("false")
       --ignore-normalizer-jq-execution-timeout-seconds duration   Set ignore normalizer JQ execution timeout
       --insecure-skip-tls-verify                                  If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure
       --kubeconfig string                                         Path to a kube config. Only required if out-of-cluster

docs/user-guide/commands/argocd_admin_app_generate-spec.md

@@ -45,6 +45,9 @@ argocd admin app generate-spec APPNAME [flags]
       --directory-exclude string                   Set glob expression used to exclude files from application source path
       --directory-include string                   Set glob expression used to include files from application source path
       --directory-recurse                          Recurse directory
+      --dry-source-path string                     Path in repository to the app directory for the dry source
+      --dry-source-repo string                     Repository URL of the app dry source
+      --dry-source-revision string                 Revision of the app dry source
       --env string                                 Application environment to monitor
   -f, --file string                                Filename or URL to Kubernetes manifests for the app
       --helm-api-versions stringArray              Helm api-versions (in format [group/]version/kind) to use when running helm template (Can be repeated to set several values: --helm-api-versions traefik.io/v1alpha1/TLSOption --helm-api-versions v1/Service). If not set, use the api-versions from the destination cluster
@@ -60,6 +63,7 @@ argocd admin app generate-spec APPNAME [flags]
       --helm-skip-tests                            Skip helm test manifests installation step
       --helm-version string                        Helm version
   -h, --help                                       help for generate-spec
+      --hydrate-to-branch string                   The branch to hydrate the app to
       --ignore-missing-value-files                 Ignore locally missing valueFiles when setting helm template --values
   -i, --inline                                     If set then generated resource is written back to the file specified in --file flag
       --jsonnet-ext-var-code stringArray           Jsonnet ext var
@@ -101,6 +105,8 @@ argocd admin app generate-spec APPNAME [flags]
       --sync-retry-backoff-factor int              Factor multiplies the base duration after each failed sync retry (default 2)
       --sync-retry-backoff-max-duration duration   Max sync retry backoff duration. Input needs to be a duration (e.g. 2m, 1h) (default 3m0s)
       --sync-retry-limit int                       Max number of allowed sync retries
+      --sync-source-branch string                  The branch from which the app will sync
+      --sync-source-path string                    The path in the repository from which the app will sync
       --validate                                   Validation of repo and cluster (default true)
       --values stringArray                         Helm values file(s) to use
       --values-literal-file string                 Filename or URL to import as a literal Helm values block

docs/user-guide/commands/argocd_app_add-source.md

@@ -28,6 +28,9 @@ argocd app add-source APPNAME [flags]
       --directory-exclude string                   Set glob expression used to exclude files from application source path
       --directory-include string                   Set glob expression used to include files from application source path
       --directory-recurse                          Recurse directory
+      --dry-source-path string                     Path in repository to the app directory for the dry source
+      --dry-source-repo string                     Repository URL of the app dry source
+      --dry-source-revision string                 Revision of the app dry source
       --env string                                 Application environment to monitor
       --helm-api-versions stringArray              Helm api-versions (in format [group/]version/kind) to use when running helm template (Can be repeated to set several values: --helm-api-versions traefik.io/v1alpha1/TLSOption --helm-api-versions v1/Service). If not set, use the api-versions from the destination cluster
       --helm-chart string                          Helm Chart name
@@ -42,6 +45,7 @@ argocd app add-source APPNAME [flags]
       --helm-skip-tests                            Skip helm test manifests installation step
       --helm-version string                        Helm version
   -h, --help                                       help for add-source
+      --hydrate-to-branch string                   The branch to hydrate the app to
       --ignore-missing-value-files                 Ignore locally missing valueFiles when setting helm template --values
       --jsonnet-ext-var-code stringArray           Jsonnet ext var
       --jsonnet-ext-var-str stringArray            Jsonnet string ext var
@@ -78,6 +82,8 @@ argocd app add-source APPNAME [flags]
       --sync-retry-backoff-factor int              Factor multiplies the base duration after each failed sync retry (default 2)
       --sync-retry-backoff-max-duration duration   Max sync retry backoff duration. Input needs to be a duration (e.g. 2m, 1h) (default 3m0s)
       --sync-retry-limit int                       Max number of allowed sync retries
+      --sync-source-branch string                  The branch from which the app will sync
+      --sync-source-path string                    The path in the repository from which the app will sync
       --validate                                   Validation of repo and cluster (default true)
       --values stringArray                         Helm values file(s) to use
       --values-literal-file string                 Filename or URL to import as a literal Helm values block

docs/user-guide/commands/argocd_app_create.md

@@ -47,6 +47,9 @@ argocd app create APPNAME [flags]
       --directory-exclude string                   Set glob expression used to exclude files from application source path
       --directory-include string                   Set glob expression used to include files from application source path
       --directory-recurse                          Recurse directory
+      --dry-source-path string                     Path in repository to the app directory for the dry source
+      --dry-source-repo string                     Repository URL of the app dry source
+      --dry-source-revision string                 Revision of the app dry source
       --env string                                 Application environment to monitor
   -f, --file string                                Filename or URL to Kubernetes manifests for the app
       --helm-api-versions stringArray              Helm api-versions (in format [group/]version/kind) to use when running helm template (Can be repeated to set several values: --helm-api-versions traefik.io/v1alpha1/TLSOption --helm-api-versions v1/Service). If not set, use the api-versions from the destination cluster
@@ -62,6 +65,7 @@ argocd app create APPNAME [flags]
       --helm-skip-tests                            Skip helm test manifests installation step
       --helm-version string                        Helm version
   -h, --help                                       help for create
+      --hydrate-to-branch string                   The branch to hydrate the app to
       --ignore-missing-value-files                 Ignore locally missing valueFiles when setting helm template --values
       --jsonnet-ext-var-code stringArray           Jsonnet ext var
       --jsonnet-ext-var-str stringArray            Jsonnet string ext var
@@ -101,6 +105,8 @@ argocd app create APPNAME [flags]
       --sync-retry-backoff-factor int              Factor multiplies the base duration after each failed sync retry (default 2)
       --sync-retry-backoff-max-duration duration   Max sync retry backoff duration. Input needs to be a duration (e.g. 2m, 1h) (default 3m0s)
       --sync-retry-limit int                       Max number of allowed sync retries
+      --sync-source-branch string                  The branch from which the app will sync
+      --sync-source-path string                    The path in the repository from which the app will sync
       --upsert                                     Allows to override application with the same name even if supplied application spec is different from existing spec
       --validate                                   Validation of repo and cluster (default true)
       --values stringArray                         Helm values file(s) to use

docs/user-guide/commands/argocd_app_set.md

@@ -40,6 +40,9 @@ argocd app set APPNAME [flags]
       --directory-exclude string                   Set glob expression used to exclude files from application source path
       --directory-include string                   Set glob expression used to include files from application source path
       --directory-recurse                          Recurse directory
+      --dry-source-path string                     Path in repository to the app directory for the dry source
+      --dry-source-repo string                     Repository URL of the app dry source
+      --dry-source-revision string                 Revision of the app dry source
       --env string                                 Application environment to monitor
       --helm-api-versions stringArray              Helm api-versions (in format [group/]version/kind) to use when running helm template (Can be repeated to set several values: --helm-api-versions traefik.io/v1alpha1/TLSOption --helm-api-versions v1/Service). If not set, use the api-versions from the destination cluster
       --helm-chart string                          Helm Chart name
@@ -54,6 +57,7 @@ argocd app set APPNAME [flags]
       --helm-skip-tests                            Skip helm test manifests installation step
       --helm-version string                        Helm version
   -h, --help                                       help for set
+      --hydrate-to-branch string                   The branch to hydrate the app to
       --ignore-missing-value-files                 Ignore locally missing valueFiles when setting helm template --values
       --jsonnet-ext-var-code stringArray           Jsonnet ext var
       --jsonnet-ext-var-str stringArray            Jsonnet string ext var
@@ -91,6 +95,8 @@ argocd app set APPNAME [flags]
       --sync-retry-backoff-factor int              Factor multiplies the base duration after each failed sync retry (default 2)
       --sync-retry-backoff-max-duration duration   Max sync retry backoff duration. Input needs to be a duration (e.g. 2m, 1h) (default 3m0s)
       --sync-retry-limit int                       Max number of allowed sync retries
+      --sync-source-branch string                  The branch from which the app will sync
+      --sync-source-path string                    The path in the repository from which the app will sync
       --validate                                   Validation of repo and cluster (default true)
       --values stringArray                         Helm values file(s) to use
       --values-literal-file string                 Filename or URL to import as a literal Helm values block

docs/user-guide/commands/argocd_app_wait.md

@@ -43,6 +43,7 @@ argocd app wait [APPNAME.. | -l selector] [flags]
       --delete                 Wait for delete
       --health                 Wait for health
   -h, --help                   help for wait
+      --hydrated               Wait for hydration operations
       --operation              Wait for pending operations
   -o, --output string          Output format. One of: json|yaml|wide|tree|tree=detailed (default "wide")
       --resource stringArray   Sync only specific resources as GROUP:KIND:NAME or !GROUP:KIND:NAME. Fields may be blank and '*' can be used. This option may be specified repeatedly

docs/user-guide/source-hydrator.md

@@ -0,0 +1,191 @@
+# Source Hydrator
+
+**Current feature state**: Alpha
+
+Tools like Helm and Kustomize allow users to express their Kubernetes manifests in a more concise and reusable way
+(keeping it DRY - Don't Repeat Yourself). However, these tools can obscure the actual Kubernetes manifests that are
+applied to the cluster.
+
+The "rendered manifest pattern" is a way to push the hydrated manifests to git before syncing them to the cluster. This
+allows users to see the actual Kubernetes manifests that are applied to the cluster.
+
+The source hydrator is a feature of Argo CD that allows users to push the hydrated manifests to git before syncing them
+to the cluster.
+
+## Enabling the Source Hydrator
+
+The source hydrator is disabled by default.
+
+To enable the source hydrator, you need to enable the "commit server" component and set the `hydrator.enabled` field in
+argocd-cmd-params-cm ConfigMap to `"true"`.
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: argocd-cmd-params-cm
+  namespace: argocd
+data:
+  hydrator.enabled: "true"
+```
+
+!!! important
+    After updating the ConfigMap, you must restart the Argo CD controller for the changes to take effect.
+
+If you are using one of the `*-install.yaml` manifests to install Argo CD, you can use the 
+`*-install-with-hydrator.yaml` version of that file instead.
+
+For example,
+
+```
+Without hydrator: https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
+With hydrator:    https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install-with-hydrator.yaml
+```
+
+!!! important
+    The `*-with-hydrator-install.yaml` manifests will eventually be removed when the source hydrator is either enabled
+    by default or removed. The upgrade guide will note if the `install-with-hydrator.yaml` manifests are no longer
+    available.
+
+## Using the Source Hydrator
+
+To use the source hydrator, you must first install a push secret.
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: my-push-secret
+  namespace: argocd
+  labels:
+    argocd.argoproj.io/secret-type: repository-write
+type: Opaque
+stringData:
+  url: "https://github.com"
+  type: "git"
+  githubAppID: "<your app ID here>"
+  githubAppInstallationID: "<your installation ID here>"
+  githubAppPrivateKey: |
+    <your private key here>
+```
+For now, the source hydrator only supports GitHub Apps. To use the source hydrator, you must first
+[create a GitHub App](https://github.com/settings/apps/new) with read/write permissions and install it in the repository
+you want to use it in. After you install the app, the installation ID will appear in the URL. The private key is
+generated when you create the GitHub App.
+Once your push secret is installed, set the `spec.sourceHydrator` field of the Application. For example:
+
+```yaml
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: my-app
+spec:
+  sourceHydrator:
+    drySource:
+      repoURL: https://github.com/argoproj/argocd-example-apps
+      path: helm-guestbook
+      targetRevision: HEAD
+    syncSource:
+      targetBranch: environments/dev
+      path: helm-guestbook
+```
+
+In this example, the hydrated manifests will be pushed to the `environments/dev` branch of the `argocd-example-apps`
+repository.
+
+!!! important "Project-Scoped Repositories"
+
+    Repository Secrets may contain a `project` field, making the secret only usable by Applications in that project.
+    The source hydrator only supports project-scoped repositories if all Applications writing to the same repository and
+    branch are in the same project. If Applications in different projects write to the same repository and branch, the
+    source hydrator will not be able to use a project-scoped repository secret and will require a global repository 
+    secret. This behavior may change in the future.
+
+If there are multiple repository-write Secrets available for a repo, the source hydrator will non-deterministically
+select one of the matching Secrets and log a warning saying "Found multiple credentials for repoURL".
+
+## Pushing to a "Staging" Branch
+
+The source hydrator can be used to push hydrated manifests to a "staging" branch instead of the `syncSource` branch.
+This provides a way to prevent the hydrated manifests from being applied to the cluster until some prerequisite
+conditions are met (in effect providing a way to handle environment promotion via Pull Requests).
+
+To use the source hydrator to push to a "staging" branch, set the `spec.sourceHydrator.hydrateTo` field of the
+Application. For example:
+
+```yaml
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: my-app
+spec:
+  project: my-project
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: default
+  sourceHydrator:
+    drySource:
+      repoURL: https://github.com/argoproj/argocd-example-apps
+      path: helm-guestbook
+      targetRevision: HEAD
+    syncSource:
+      targetBranch: environments/dev
+      path: helm-guestbook
+    hydrateTo:
+      targetBranch: environments/dev-next
+```
+
+In this example, the hydrated manifests will be pushed to the `environments/dev-next` branch, and Argo CD will not sync
+the changes until something moves them to the `environments/dev` branch.
+
+You could use a CI action to move the hydrated manifests from the `hydrateTo` branch to the `syncSource` branch. To
+introduce a gating mechanism, you could require a Pull Request to be opened to merge the changes from the `hydrateTo`
+branch to the `syncSource` branch.
+
+Argo CD will only push changes to the `hydrateTo` branch, it will not create a PR or otherwise facilitate moving those 
+changes to the `syncSource` branch. You will need to use your own tooling to move the changes from the `hydrateTo` 
+branch to the `syncSource` branch.
+
+## Limitations
+
+### Project-Scoped Push Secrets
+
+If all the Applications for a given destination repo/branch are under the same project, then the hydrator will use any
+available project-scoped push secrets. If two Applications for a given repo/branch are in different projects, then the
+hydrator will not be able to use a project-scoped push secret and will require a global push secret.
+
+### Credential Templates
+
+Credential templates allow a single credential to be used for multiple repositories. The source hydrator does not 
+currently support credential templates. You will need a separate credential for each repository.
+
+## Prerequisites
+
+### Handle Secrets on the Destination Cluster
+
+Do not use the source hydrator with any tool that injects secrets into your manifests as part of the hydration process
+(for example, Helm with SOPS or the Argo CD Vault Plugin). These secrets would be committed to git. Instead, use a
+secrets operator that populates the secret values on the destination cluster.
+
+## Best Practices
+
+### Make Hydration Deterministic
+
+The source hydrator should be deterministic. For a given dry source commit, the hydrator should always produce the same
+hydrated manifests. This means that the hydrator should not rely on external state or configuration that is not stored
+in git.
+
+Examples of non-deterministic hydration:
+
+* A Helm chart using unpinned dependencies
+* A Helm chart is using a non-deterministic template function such as `randAlphaNum` or `lookup`
+* [Config Management Plugins](../operator-manual/config-management-plugins.md) which retrieve non-git state, such as secrets
+* Kustomize manifests referencing unpinned remote bases
+
+### Enable Branch Protection
+
+Argo CD should be the only thing pushing hydrated manifests to the hydrated branches. To prevent other tools or users
+from pushing to the hydrated branches, enable branch protection in your SCM.
+
+It is best practice to prefix the hydrated branches with a common prefix, such as `environment/`. This makes it easier
+to configure branch protection rules on the destination repository.

go.mod

@@ -43,7 +43,7 @@ require (
 	github.com/golang/protobuf v1.5.4
 	github.com/google/btree v1.1.3
 	github.com/google/go-cmp v0.6.0
-	github.com/google/go-github/v63 v63.0.0
+	github.com/google/go-github/v66 v66.0.0
 	github.com/google/go-jsonnet v0.20.0
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/google/uuid v1.6.0
@@ -139,7 +139,6 @@ require (
 	github.com/go-jose/go-jose/v4 v4.0.2 // indirect
 	github.com/golang-jwt/jwt/v5 v5.2.1 // indirect
 	github.com/google/gnostic-models v0.6.8 // indirect
-	github.com/google/go-github/v66 v66.0.0 // indirect
 	github.com/google/s2a-go v0.1.7 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
 	github.com/googleapis/gax-go/v2 v2.12.3 // indirect

go.sum

@@ -437,8 +437,6 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-github/v41 v41.0.0 h1:HseJrM2JFf2vfiZJ8anY2hqBjdfY1Vlj/K27ueww4gg=
 github.com/google/go-github/v41 v41.0.0/go.mod h1:XgmCA5H323A9rtgExdTcnDkcqp6S30AVACCBDOonIxg=
-github.com/google/go-github/v63 v63.0.0 h1:13xwK/wk9alSokujB9lJkuzdmQuVn2QCPeck76wR3nE=
-github.com/google/go-github/v63 v63.0.0/go.mod h1:IqbcrgUmIcEaioWrGYei/09o+ge5vhffGOcxrO0AfmA=
 github.com/google/go-github/v66 v66.0.0 h1:ADJsaXj9UotwdgK8/iFZtv7MLc8E8WBl62WLd/D/9+M=
 github.com/google/go-github/v66 v66.0.0/go.mod h1:+4SO9Zkuyf8ytMj0csN1NR/5OTR+MfqPp8P8dVlcvY4=
 github.com/google/go-jsonnet v0.20.0 h1:WG4TTSARuV7bSm4PMB4ohjxe33IHT5WVTrJSU33uT4g=

hack/generate-proto.sh

@@ -95,7 +95,7 @@ MOD_ROOT=${GOPATH}/pkg/mod
 grpc_gateway_version=$(go list -m github.com/grpc-ecosystem/grpc-gateway | awk '{print $NF}' | head -1)
 GOOGLE_PROTO_API_PATH=${MOD_ROOT}/github.com/grpc-ecosystem/grpc-gateway@${grpc_gateway_version}/third_party/googleapis
 GOGO_PROTOBUF_PATH=${PROJECT_ROOT}/vendor/github.com/gogo/protobuf
-PROTO_FILES=$(find "$PROJECT_ROOT" \( -name "*.proto" -and -path '*/server/*' -or -path '*/reposerver/*' -and -name "*.proto" -or -path '*/cmpserver/*' -and -name "*.proto" \) | sort)
+PROTO_FILES=$(find "$PROJECT_ROOT" \( -name "*.proto" -and -path '*/server/*' -or -path '*/reposerver/*' -and -name "*.proto" -or -path '*/cmpserver/*' -and -name "*.proto" -or -path '*/commitserver/*' -and -name "*.proto" -or -path '*/util/askpass/*' -and -name "*.proto" \) | sort)
 for i in ${PROTO_FILES}; do
     protoc \
         -I"${PROJECT_ROOT}" \
@@ -110,6 +110,9 @@ for i in ${PROTO_FILES}; do
         "$i"
 done
 
+# This file is generated but should not be checked in.
+rm util/askpass/askpass.swagger.json
+
 [ -L "${GOPATH_PROJECT_ROOT}" ] && rm -rf "${GOPATH_PROJECT_ROOT}"
 [ -L ./v2 ] && rm -rf v2
 
@@ -162,3 +165,4 @@ clean_swagger server
 clean_swagger reposerver
 clean_swagger controller
 clean_swagger cmpserver
+clean_swagger commitserver

hack/update-manifests.sh

@@ -49,3 +49,21 @@ $KUSTOMIZE build "${SRCROOT}/manifests/ha/namespace-install" >> "${SRCROOT}/mani
 
 echo "${AUTOGENMSG}" > "${SRCROOT}/manifests/core-install.yaml"
 $KUSTOMIZE build "${SRCROOT}/manifests/core-install" >> "${SRCROOT}/manifests/core-install.yaml"
+
+# Copies enabling manifest hydrator. These can be removed once the manifest hydrator is either removed or enabled by 
+# default.
+
+echo "${AUTOGENMSG}" > "${SRCROOT}/manifests/install-with-hydrator.yaml"
+$KUSTOMIZE build "${SRCROOT}/manifests/cluster-install-with-hydrator" >> "${SRCROOT}/manifests/install-with-hydrator.yaml"
+
+echo "${AUTOGENMSG}" > "${SRCROOT}/manifests/namespace-install-with-hydrator.yaml"
+$KUSTOMIZE build "${SRCROOT}/manifests/namespace-install-with-hydrator" >> "${SRCROOT}/manifests/namespace-install-with-hydrator.yaml"
+
+echo "${AUTOGENMSG}" > "${SRCROOT}/manifests/ha/install-with-hydrator.yaml"
+$KUSTOMIZE build "${SRCROOT}/manifests/ha/cluster-install-with-hydrator" >> "${SRCROOT}/manifests/ha/install-with-hydrator.yaml"
+
+echo "${AUTOGENMSG}" > "${SRCROOT}/manifests/ha/namespace-install-with-hydrator.yaml"
+$KUSTOMIZE build "${SRCROOT}/manifests/ha/namespace-install-with-hydrator" >> "${SRCROOT}/manifests/ha/namespace-install-with-hydrator.yaml"
+
+echo "${AUTOGENMSG}" > "${SRCROOT}/manifests/core-install-with-hydrator.yaml"
+$KUSTOMIZE build "${SRCROOT}/manifests/core-install-with-hydrator" >> "${SRCROOT}/manifests/core-install-with-hydrator.yaml"

manifests/base/application-controller-deployment/argocd-application-controller-deployment.yaml

@@ -223,6 +223,12 @@ spec:
               name: argocd-cmd-params-cm
               key: controller.diff.server.side
               optional: true
+        - name: ARGOCD_HYDRATOR_ENABLED
+          valueFrom:
+            configMapKeyRef:
+              name: argocd-cmd-params-cm
+              key: hydrator.enabled
+              optional: true
         image: quay.io/argoproj/argocd:latest
         imagePullPolicy: Always
         name: argocd-application-controller

manifests/base/application-controller/argocd-application-controller-statefulset.yaml

@@ -232,6 +232,12 @@ spec:
               name: argocd-cmd-params-cm
               key: controller.ignore.normalizer.jq.timeout
               optional: true
+        - name: ARGOCD_HYDRATOR_ENABLED
+          valueFrom:
+            configMapKeyRef:
+              name: argocd-cmd-params-cm
+              key: hydrator.enabled
+              optional: true
         - name: KUBECACHEDIR
           value: /tmp/kubecache
         image: quay.io/argoproj/argocd:latest

manifests/base/commit-server/argocd-commit-server-deployment.yaml

@@ -0,0 +1,150 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app.kubernetes.io/name: argocd-commit-server
+    app.kubernetes.io/part-of: argocd
+    app.kubernetes.io/component: commit-server
+  name: argocd-commit-server
+spec:
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: argocd-commit-server
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: argocd-commit-server
+    spec:
+      serviceAccountName: argocd-commit-server
+      automountServiceAccountToken: false
+      containers:
+      - name: argocd-commit-server
+        image: quay.io/argoproj/argocd:latest
+        imagePullPolicy: Always
+        args:
+          - /usr/local/bin/argocd-commit-server
+        env:
+          - name: ARGOCD_COMMIT_SERVER_LISTEN_ADDRESS
+            valueFrom:
+              configMapKeyRef:
+                name: argocd-cmd-params-cm
+                key: commitserver.listen.address
+                optional: true
+          - name: ARGOCD_COMMIT_SERVER_METRICS_LISTEN_ADDRESS
+            valueFrom:
+              configMapKeyRef:
+                name: argocd-cmd-params-cm
+                key: commitserver.metrics.listen.address
+                optional: true
+          - name: ARGOCD_COMMIT_SERVER_LOGFORMAT
+            valueFrom:
+              configMapKeyRef:
+                name: argocd-cmd-params-cm
+                key: commitserver.log.format
+                optional: true
+          - name: ARGOCD_COMMIT_SERVER_LOGLEVEL
+            valueFrom:
+              configMapKeyRef:
+                name: argocd-cmd-params-cm
+                key: commitserver.log.level
+                optional: true
+        ports:
+        - containerPort: 8086
+        - containerPort: 8087
+        livenessProbe:
+          httpGet:
+            path: /healthz?full=true
+            port: 8087
+          initialDelaySeconds: 30
+          periodSeconds: 30
+          failureThreshold: 3
+          timeoutSeconds: 5
+        readinessProbe:
+          httpGet:
+            path: /healthz
+            port: 8087
+          initialDelaySeconds: 5
+          periodSeconds: 10
+        securityContext:
+          runAsNonRoot: true
+          readOnlyRootFilesystem: true
+          allowPrivilegeEscalation: false
+          capabilities:
+            drop:
+            - ALL
+          seccompProfile:
+            type: RuntimeDefault
+        volumeMounts:
+        - name: ssh-known-hosts
+          mountPath: /app/config/ssh
+        - name: tls-certs
+          mountPath: /app/config/tls
+        - name: gpg-keys
+          mountPath: /app/config/gpg/source
+        - name: gpg-keyring
+          mountPath: /app/config/gpg/keys
+        # We need a writeable temp directory for the askpass socket file.
+        - name: tmp
+          mountPath: /tmp
+      initContainers:
+      - command:
+        - /bin/cp
+        - -n
+        - /usr/local/bin/argocd
+        - /var/run/argocd/argocd-cmp-server
+        image: quay.io/argoproj/argocd:latest
+        name: copyutil
+        securityContext:
+          runAsNonRoot: true
+          readOnlyRootFilesystem: true
+          allowPrivilegeEscalation: false
+          capabilities:
+            drop:
+            - ALL
+          seccompProfile:
+            type: RuntimeDefault
+        volumeMounts:
+        - mountPath: /var/run/argocd
+          name: var-files
+      volumes:
+        - name: ssh-known-hosts
+          configMap:
+            name: argocd-ssh-known-hosts-cm
+        - name: tls-certs
+          configMap:
+            name: argocd-tls-certs-cm
+        - name: gpg-keys
+          configMap:
+            name: argocd-gpg-keys-cm
+        - name: gpg-keyring
+          emptyDir: {}
+        - name: tmp
+          emptyDir: {}
+        - name: argocd-commit-server-tls
+          secret:
+            secretName: argocd-commit-server-tls
+            optional: true
+            items:
+            - key: tls.crt
+              path: tls.crt
+            - key: tls.key
+              path: tls.key
+            - key: ca.crt
+              path: ca.crt
+        - emptyDir: {}
+          name: var-files
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchLabels:
+                  app.kubernetes.io/name: argocd-commit-server
+              topologyKey: kubernetes.io/hostname
+          - weight: 5
+            podAffinityTerm:
+              labelSelector:
+                matchLabels:
+                  app.kubernetes.io/part-of: argocd
+              topologyKey: kubernetes.io/hostname

manifests/base/commit-server/argocd-commit-server-network-policy.yaml

@@ -0,0 +1,22 @@
+kind: NetworkPolicy
+apiVersion: networking.k8s.io/v1
+metadata:
+  name: argocd-commit-server-network-policy
+spec:
+  podSelector:
+    matchLabels:
+      app.kubernetes.io/name: argocd-commit-server
+  policyTypes:
+    - Ingress
+  ingress:
+    - from:
+        - podSelector:
+            matchLabels:
+              app.kubernetes.io/name: argocd-application-controller
+      ports:
+        - protocol: TCP
+          port: 8086
+    - from:
+        - namespaceSelector: { }
+      ports:
+        - port: 8087

manifests/base/commit-server/argocd-commit-server-sa.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  labels:
+    app.kubernetes.io/name: argocd-commit-server
+    app.kubernetes.io/part-of: argocd
+    app.kubernetes.io/component: commit-server
+  name: argocd-commit-server

manifests/base/commit-server/argocd-commit-server-service.yaml

@@ -0,0 +1,20 @@
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app.kubernetes.io/name: argocd-commit-server
+    app.kubernetes.io/part-of: argocd
+    app.kubernetes.io/component: commit-server
+  name: argocd-commit-server
+spec:
+  ports:
+  - name: server
+    protocol: TCP
+    port: 8086
+    targetPort: 8086
+  - name: metrics
+    protocol: TCP
+    port: 8087
+    targetPort: 8087
+  selector:
+    app.kubernetes.io/name: argocd-commit-server

manifests/base/commit-server/kustomization.yaml

@@ -0,0 +1,8 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+- argocd-commit-server-sa.yaml
+- argocd-commit-server-deployment.yaml
+- argocd-commit-server-service.yaml
+- argocd-commit-server-network-policy.yaml

manifests/cluster-install-with-hydrator/kustomization.yaml

@@ -0,0 +1,12 @@
+resources:
+  - ../cluster-install
+  - ../base/commit-server
+
+patches:
+  - target:
+      kind: ConfigMap
+      name: argocd-cmd-params-cm
+    patch: |-
+      - op: add
+        path: /data
+        value: {"hydrator.enabled": "true"}

manifests/core-install-with-hydrator/kustomization.yaml

@@ -0,0 +1,12 @@
+resources:
+  - ../core-install
+  - ../base/commit-server
+
+patches:
+  - target:
+      kind: ConfigMap
+      name: argocd-cmd-params-cm
+    patch: |-
+      - op: add
+        path: /data
+        value: {"hydrator.enabled": "true"}

manifests/crds/application-crd.yaml

@@ -1403,6 +1403,64 @@ spec:
                 required:
                 - repoURL
                 type: object
+              sourceHydrator:
+                description: SourceHydrator provides a way to push hydrated manifests
+                  back to git before syncing them to the cluster.
+                properties:
+                  drySource:
+                    description: DrySource specifies where the dry "don't repeat yourself"
+                      manifest source lives.
+                    properties:
+                      path:
+                        description: Path is a directory path within the Git repository
+                          where the manifests are located
+                        type: string
+                      repoURL:
+                        description: RepoURL is the URL to the git repository that
+                          contains the application manifests
+                        type: string
+                      targetRevision:
+                        description: TargetRevision defines the revision of the source
+                          to hydrate
+                        type: string
+                    required:
+                    - path
+                    - repoURL
+                    - targetRevision
+                    type: object
+                  hydrateTo:
+                    description: |-
+                      HydrateTo specifies an optional "staging" location to push hydrated manifests to. An external system would then
+                      have to move manifests to the SyncSource, e.g. by pull request.
+                    properties:
+                      targetBranch:
+                        description: TargetBranch is the branch to which hydrated
+                          manifests should be committed
+                        type: string
+                    required:
+                    - targetBranch
+                    type: object
+                  syncSource:
+                    description: SyncSource specifies where to sync hydrated manifests
+                      from.
+                    properties:
+                      path:
+                        description: |-
+                          Path is a directory path within the git repository where hydrated manifests should be committed to and synced
+                          from. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.
+                        type: string
+                      targetBranch:
+                        description: TargetBranch is the branch to which hydrated
+                          manifests should be committed
+                        type: string
+                    required:
+                    - path
+                    - targetBranch
+                    type: object
+                required:
+                - drySource
+                - syncSource
+                type: object
               sources:
                 description: Sources is a reference to the location of the application's
                   manifests or chart
@@ -4616,6 +4674,177 @@ spec:
                       type: string
                   type: object
                 type: array
+              sourceHydrator:
+                description: SourceHydrator stores information about the current state
+                  of source hydration
+                properties:
+                  currentOperation:
+                    description: CurrentOperation holds the status of the hydrate
+                      operation
+                    properties:
+                      drySHA:
+                        description: DrySHA holds the resolved revision (sha) of the
+                          dry source as of the most recent reconciliation
+                        type: string
+                      finishedAt:
+                        description: FinishedAt indicates when the hydrate operation
+                          finished
+                        format: date-time
+                        type: string
+                      hydratedSHA:
+                        description: HydratedSHA holds the resolved revision (sha)
+                          of the hydrated source as of the most recent reconciliation
+                        type: string
+                      message:
+                        description: Message contains a message describing the current
+                          status of the hydrate operation
+                        type: string
+                      phase:
+                        description: Phase indicates the status of the hydrate operation
+                        enum:
+                        - Hydrating
+                        - Failed
+                        - Hydrated
+                        type: string
+                      sourceHydrator:
+                        description: SourceHydrator holds the hydrator config used
+                          for the hydrate operation
+                        properties:
+                          drySource:
+                            description: DrySource specifies where the dry "don't
+                              repeat yourself" manifest source lives.
+                            properties:
+                              path:
+                                description: Path is a directory path within the Git
+                                  repository where the manifests are located
+                                type: string
+                              repoURL:
+                                description: RepoURL is the URL to the git repository
+                                  that contains the application manifests
+                                type: string
+                              targetRevision:
+                                description: TargetRevision defines the revision of
+                                  the source to hydrate
+                                type: string
+                            required:
+                            - path
+                            - repoURL
+                            - targetRevision
+                            type: object
+                          hydrateTo:
+                            description: |-
+                              HydrateTo specifies an optional "staging" location to push hydrated manifests to. An external system would then
+                              have to move manifests to the SyncSource, e.g. by pull request.
+                            properties:
+                              targetBranch:
+                                description: TargetBranch is the branch to which hydrated
+                                  manifests should be committed
+                                type: string
+                            required:
+                            - targetBranch
+                            type: object
+                          syncSource:
+                            description: SyncSource specifies where to sync hydrated
+                              manifests from.
+                            properties:
+                              path:
+                                description: |-
+                                  Path is a directory path within the git repository where hydrated manifests should be committed to and synced
+                                  from. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.
+                                type: string
+                              targetBranch:
+                                description: TargetBranch is the branch to which hydrated
+                                  manifests should be committed
+                                type: string
+                            required:
+                            - path
+                            - targetBranch
+                            type: object
+                        required:
+                        - drySource
+                        - syncSource
+                        type: object
+                      startedAt:
+                        description: StartedAt indicates when the hydrate operation
+                          started
+                        format: date-time
+                        type: string
+                    required:
+                    - message
+                    - phase
+                    type: object
+                  lastSuccessfulOperation:
+                    description: LastSuccessfulOperation holds info about the most
+                      recent successful hydration
+                    properties:
+                      drySHA:
+                        description: DrySHA holds the resolved revision (sha) of the
+                          dry source as of the most recent reconciliation
+                        type: string
+                      hydratedSHA:
+                        description: HydratedSHA holds the resolved revision (sha)
+                          of the hydrated source as of the most recent reconciliation
+                        type: string
+                      sourceHydrator:
+                        description: SourceHydrator holds the hydrator config used
+                          for the hydrate operation
+                        properties:
+                          drySource:
+                            description: DrySource specifies where the dry "don't
+                              repeat yourself" manifest source lives.
+                            properties:
+                              path:
+                                description: Path is a directory path within the Git
+                                  repository where the manifests are located
+                                type: string
+                              repoURL:
+                                description: RepoURL is the URL to the git repository
+                                  that contains the application manifests
+                                type: string
+                              targetRevision:
+                                description: TargetRevision defines the revision of
+                                  the source to hydrate
+                                type: string
+                            required:
+                            - path
+                            - repoURL
+                            - targetRevision
+                            type: object
+                          hydrateTo:
+                            description: |-
+                              HydrateTo specifies an optional "staging" location to push hydrated manifests to. An external system would then
+                              have to move manifests to the SyncSource, e.g. by pull request.
+                            properties:
+                              targetBranch:
+                                description: TargetBranch is the branch to which hydrated
+                                  manifests should be committed
+                                type: string
+                            required:
+                            - targetBranch
+                            type: object
+                          syncSource:
+                            description: SyncSource specifies where to sync hydrated
+                              manifests from.
+                            properties:
+                              path:
+                                description: |-
+                                  Path is a directory path within the git repository where hydrated manifests should be committed to and synced
+                                  from. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.
+                                type: string
+                              targetBranch:
+                                description: TargetBranch is the branch to which hydrated
+                                  manifests should be committed
+                                type: string
+                            required:
+                            - path
+                            - targetBranch
+                            type: object
+                        required:
+                        - drySource
+                        - syncSource
+                        type: object
+                    type: object
+                type: object
               sourceType:
                 description: SourceType specifies the type of this application
                 type: string

manifests/ha/cluster-install-with-hydrator/kustomization.yaml

@@ -0,0 +1,3 @@
+resources:
+  - ../cluster-install
+  - ../../base/commit-server

manifests/ha/install-with-hydrator/kustomization.yaml

@@ -0,0 +1,3 @@
+resources:
+  - ../base
+  - ../../base/commit-server

manifests/ha/namespace-install-with-hydrator/kustomization.yaml

@@ -0,0 +1,3 @@
+resources:
+  - ../namespace-install
+  - ../../base/commit-server

manifests/ha/namespace-install.yaml

@@ -3083,6 +3083,12 @@ spec:
               key: controller.ignore.normalizer.jq.timeout
               name: argocd-cmd-params-cm
               optional: true
+        - name: ARGOCD_HYDRATOR_ENABLED
+          valueFrom:
+            configMapKeyRef:
+              key: hydrator.enabled
+              name: argocd-cmd-params-cm
+              optional: true
         - name: KUBECACHEDIR
           value: /tmp/kubecache
         image: quay.io/argoproj/argocd:latest

manifests/namespace-install-with-hydrator/kustomization.yaml

@@ -0,0 +1,12 @@
+resources:
+  - ../namespace-install
+  - ../base/commit-server
+
+patches:
+  - target:
+      kind: ConfigMap
+      name: argocd-cmd-params-cm
+    patch: |-
+      - op: add
+        path: /data
+        value: {"hydrator.enabled": "true"}

manifests/namespace-install.yaml

@@ -2153,6 +2153,12 @@ spec:
               key: controller.ignore.normalizer.jq.timeout
               name: argocd-cmd-params-cm
               optional: true
+        - name: ARGOCD_HYDRATOR_ENABLED
+          valueFrom:
+            configMapKeyRef:
+              key: hydrator.enabled
+              name: argocd-cmd-params-cm
+              optional: true
         - name: KUBECACHEDIR
           value: /tmp/kubecache
         image: quay.io/argoproj/argocd:latest

pkg/apis/application/v1alpha1/application_annotations.go

@@ -4,6 +4,8 @@ const (
 	// AnnotationKeyRefresh is the annotation key which indicates that app needs to be refreshed. Removed by application controller after app is refreshed.
 	// Might take values 'normal'/'hard'. Value 'hard' means manifest cache and target cluster state cache should be invalidated before refresh.
 	AnnotationKeyRefresh string = "argocd.argoproj.io/refresh"
+	// AnnotationKeyHydrate is the annotation key which indicates that app needs to be hydrated. Removed by application controller after app is hydrated.
+	AnnotationKeyHydrate string = "argocd.argoproj.io/hydrate"
 
 	// AnnotationKeyManifestGeneratePaths is an annotation that contains a list of semicolon-separated paths in the
 	// manifests repository that affects the manifest generation. Paths might be either relative or absolute. The

pkg/apis/application/v1alpha1/generated.proto

@@ -644,6 +644,9 @@ message ApplicationSpec {
 
   // Sources is a reference to the location of the application's manifests or chart
   repeated ApplicationSource sources = 8;
+
+  // SourceHydrator provides a way to push hydrated manifests back to git before syncing them to the cluster.
+  optional SourceHydrator sourceHydrator = 9;
 }
 
 // ApplicationStatus contains status information for the application
@@ -687,6 +690,9 @@ message ApplicationStatus {
 
   // ControllerNamespace indicates the namespace in which the application controller is located
   optional string controllerNamespace = 13;
+
+  // SourceHydrator stores information about the current state of source hydration
+  optional SourceHydratorStatus sourceHydrator = 14;
 }
 
 // ApplicationSummary contains information about URLs and container images used by an application
@@ -957,6 +963,18 @@ message ConnectionState {
   optional .k8s.io.apimachinery.pkg.apis.meta.v1.Time attemptedAt = 3;
 }
 
+// DrySource specifies a location for dry "don't repeat yourself" manifest source information.
+message DrySource {
+  // RepoURL is the URL to the git repository that contains the application manifests
+  optional string repoURL = 1;
+
+  // TargetRevision defines the revision of the source to hydrate
+  optional string targetRevision = 2;
+
+  // Path is a directory path within the Git repository where the manifests are located
+  optional string path = 3;
+}
+
 // DuckType defines a generator to match against clusters registered with ArgoCD.
 message DuckTypeGenerator {
   // ConfigMapRef is a ConfigMap with the duck type definitions needed to retrieve the data
@@ -1125,6 +1143,37 @@ message HostResourceInfo {
   optional int64 capacity = 4;
 }
 
+// HydrateOperation contains information about the most recent hydrate operation
+message HydrateOperation {
+  // StartedAt indicates when the hydrate operation started
+  optional .k8s.io.apimachinery.pkg.apis.meta.v1.Time startedAt = 1;
+
+  // FinishedAt indicates when the hydrate operation finished
+  optional .k8s.io.apimachinery.pkg.apis.meta.v1.Time finishedAt = 2;
+
+  // Phase indicates the status of the hydrate operation
+  optional string phase = 3;
+
+  // Message contains a message describing the current status of the hydrate operation
+  optional string message = 4;
+
+  // DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation
+  optional string drySHA = 5;
+
+  // HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation
+  optional string hydratedSHA = 6;
+
+  // SourceHydrator holds the hydrator config used for the hydrate operation
+  optional SourceHydrator sourceHydrator = 7;
+}
+
+// HydrateTo specifies a location to which hydrated manifests should be pushed as a "staging area" before being moved to
+// the SyncSource. The RepoURL and Path are assumed based on the associated SyncSource config in the SourceHydrator.
+message HydrateTo {
+  // TargetBranch is the branch to which hydrated manifests should be committed
+  optional string targetBranch = 1;
+}
+
 message Info {
   optional string name = 1;
 
@@ -2244,6 +2293,41 @@ message SignatureKey {
   optional string keyID = 1;
 }
 
+// SourceHydrator specifies a dry "don't repeat yourself" source for manifests, a sync source from which to sync
+// hydrated manifests, and an optional hydrateTo location to act as a "staging" aread for hydrated manifests.
+message SourceHydrator {
+  // DrySource specifies where the dry "don't repeat yourself" manifest source lives.
+  optional DrySource drySource = 1;
+
+  // SyncSource specifies where to sync hydrated manifests from.
+  optional SyncSource syncSource = 2;
+
+  // HydrateTo specifies an optional "staging" location to push hydrated manifests to. An external system would then
+  // have to move manifests to the SyncSource, e.g. by pull request.
+  optional HydrateTo hydrateTo = 3;
+}
+
+// SourceHydratorStatus contains information about the current state of source hydration
+message SourceHydratorStatus {
+  // LastSuccessfulOperation holds info about the most recent successful hydration
+  optional SuccessfulHydrateOperation lastSuccessfulOperation = 1;
+
+  // CurrentOperation holds the status of the hydrate operation
+  optional HydrateOperation currentOperation = 2;
+}
+
+// SuccessfulHydrateOperation contains information about the most recent successful hydrate operation
+message SuccessfulHydrateOperation {
+  // DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation
+  optional string drySHA = 5;
+
+  // HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation
+  optional string hydratedSHA = 6;
+
+  // SourceHydrator holds the hydrator config used for the hydrate operation
+  optional SourceHydrator sourceHydrator = 7;
+}
+
 // SyncOperation contains details about a sync operation.
 message SyncOperation {
   // Revision is the revision (Git) or chart version (Helm) which to sync the application to
@@ -2343,6 +2427,17 @@ message SyncPolicyAutomated {
   optional bool allowEmpty = 3;
 }
 
+// SyncSource specifies a location from which hydrated manifests may be synced. RepoURL is assumed based on the
+// associated DrySource config in the SourceHydrator.
+message SyncSource {
+  // TargetBranch is the branch to which hydrated manifests should be committed
+  optional string targetBranch = 1;
+
+  // Path is a directory path within the git repository where hydrated manifests should be committed to and synced
+  // from. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.
+  optional string path = 2;
+}
+
 // SyncStatus contains information about the currently observed live and desired states of an application
 message SyncStatus {
   // Status is the sync state of the comparison

pkg/apis/application/v1alpha1/openapi_generated.go

@@ -72,6 +72,7 @@ func GetOpenAPIDefinitions(ref common.ReferenceCallback) map[string]common.OpenA
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ConfigManagementPlugin":                  schema_pkg_apis_application_v1alpha1_ConfigManagementPlugin(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ConfigMapKeyRef":                         schema_pkg_apis_application_v1alpha1_ConfigMapKeyRef(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ConnectionState":                         schema_pkg_apis_application_v1alpha1_ConnectionState(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.DrySource":                               schema_pkg_apis_application_v1alpha1_DrySource(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.DuckTypeGenerator":                       schema_pkg_apis_application_v1alpha1_DuckTypeGenerator(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.EnvEntry":                                schema_pkg_apis_application_v1alpha1_EnvEntry(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ErrApplicationNotAllowedToUseProject":    schema_pkg_apis_application_v1alpha1_ErrApplicationNotAllowedToUseProject(ref),
@@ -87,6 +88,8 @@ func GetOpenAPIDefinitions(ref common.ReferenceCallback) map[string]common.OpenA
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HelmParameter":                           schema_pkg_apis_application_v1alpha1_HelmParameter(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HostInfo":                                schema_pkg_apis_application_v1alpha1_HostInfo(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HostResourceInfo":                        schema_pkg_apis_application_v1alpha1_HostResourceInfo(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HydrateOperation":                        schema_pkg_apis_application_v1alpha1_HydrateOperation(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HydrateTo":                               schema_pkg_apis_application_v1alpha1_HydrateTo(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.Info":                                    schema_pkg_apis_application_v1alpha1_Info(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.InfoItem":                                schema_pkg_apis_application_v1alpha1_InfoItem(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.JWTToken":                                schema_pkg_apis_application_v1alpha1_JWTToken(ref),
@@ -158,11 +161,15 @@ func GetOpenAPIDefinitions(ref common.ReferenceCallback) map[string]common.OpenA
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SCMProviderGeneratorGitlab":              schema_pkg_apis_application_v1alpha1_SCMProviderGeneratorGitlab(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SecretRef":                               schema_pkg_apis_application_v1alpha1_SecretRef(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SignatureKey":                            schema_pkg_apis_application_v1alpha1_SignatureKey(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator":                          schema_pkg_apis_application_v1alpha1_SourceHydrator(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydratorStatus":                    schema_pkg_apis_application_v1alpha1_SourceHydratorStatus(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SuccessfulHydrateOperation":              schema_pkg_apis_application_v1alpha1_SuccessfulHydrateOperation(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncOperation":                           schema_pkg_apis_application_v1alpha1_SyncOperation(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncOperationResource":                   schema_pkg_apis_application_v1alpha1_SyncOperationResource(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncOperationResult":                     schema_pkg_apis_application_v1alpha1_SyncOperationResult(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncPolicy":                              schema_pkg_apis_application_v1alpha1_SyncPolicy(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncPolicyAutomated":                     schema_pkg_apis_application_v1alpha1_SyncPolicyAutomated(ref),
+		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncSource":                              schema_pkg_apis_application_v1alpha1_SyncSource(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncStatus":                              schema_pkg_apis_application_v1alpha1_SyncStatus(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncStrategy":                            schema_pkg_apis_application_v1alpha1_SyncStrategy(ref),
 		"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncStrategyApply":                       schema_pkg_apis_application_v1alpha1_SyncStrategyApply(ref),
@@ -2317,12 +2324,18 @@ func schema_pkg_apis_application_v1alpha1_ApplicationSpec(ref common.ReferenceCa
 							},
 						},
 					},
+					"sourceHydrator": {
+						SchemaProps: spec.SchemaProps{
+							Description: "SourceHydrator provides a way to push hydrated manifests back to git before syncing them to the cluster.",
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator"),
+						},
+					},
 				},
 				Required: []string{"destination", "project"},
 			},
 		},
 		Dependencies: []string{
-			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationDestination", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationSource", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.Info", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ResourceIgnoreDifferences", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncPolicy"},
+			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationDestination", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationSource", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.Info", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ResourceIgnoreDifferences", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncPolicy"},
 	}
 }
 
@@ -2450,11 +2463,18 @@ func schema_pkg_apis_application_v1alpha1_ApplicationStatus(ref common.Reference
 							Format:      "",
 						},
 					},
+					"sourceHydrator": {
+						SchemaProps: spec.SchemaProps{
+							Description: "SourceHydrator stores information about the current state of source hydration",
+							Default:     map[string]interface{}{},
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydratorStatus"),
+						},
+					},
 				},
 			},
 		},
 		Dependencies: []string{
-			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationCondition", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationSummary", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HealthStatus", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.OperationState", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ResourceStatus", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.RevisionHistory", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncStatus", "k8s.io/apimachinery/pkg/apis/meta/v1.Time"},
+			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationCondition", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ApplicationSummary", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HealthStatus", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.OperationState", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.ResourceStatus", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.RevisionHistory", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydratorStatus", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncStatus", "k8s.io/apimachinery/pkg/apis/meta/v1.Time"},
 	}
 }
 
@@ -3346,6 +3366,44 @@ func schema_pkg_apis_application_v1alpha1_ConnectionState(ref common.ReferenceCa
 	}
 }
 
+func schema_pkg_apis_application_v1alpha1_DrySource(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "DrySource specifies a location for dry \"don't repeat yourself\" manifest source information.",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"repoURL": {
+						SchemaProps: spec.SchemaProps{
+							Description: "RepoURL is the URL to the git repository that contains the application manifests",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"targetRevision": {
+						SchemaProps: spec.SchemaProps{
+							Description: "TargetRevision defines the revision of the source to hydrate",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"path": {
+						SchemaProps: spec.SchemaProps{
+							Description: "Path is a directory path within the Git repository where the manifests are located",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+				},
+				Required: []string{"repoURL", "targetRevision", "path"},
+			},
+		},
+	}
+}
+
 func schema_pkg_apis_application_v1alpha1_DuckTypeGenerator(ref common.ReferenceCallback) common.OpenAPIDefinition {
 	return common.OpenAPIDefinition{
 		Schema: spec.Schema{
@@ -3966,6 +4024,93 @@ func schema_pkg_apis_application_v1alpha1_HostResourceInfo(ref common.ReferenceC
 	}
 }
 
+func schema_pkg_apis_application_v1alpha1_HydrateOperation(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "HydrateOperation contains information about the most recent hydrate operation",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"startedAt": {
+						SchemaProps: spec.SchemaProps{
+							Description: "StartedAt indicates when the hydrate operation started",
+							Ref:         ref("k8s.io/apimachinery/pkg/apis/meta/v1.Time"),
+						},
+					},
+					"finishedAt": {
+						SchemaProps: spec.SchemaProps{
+							Description: "FinishedAt indicates when the hydrate operation finished",
+							Ref:         ref("k8s.io/apimachinery/pkg/apis/meta/v1.Time"),
+						},
+					},
+					"phase": {
+						SchemaProps: spec.SchemaProps{
+							Description: "Phase indicates the status of the hydrate operation",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"message": {
+						SchemaProps: spec.SchemaProps{
+							Description: "Message contains a message describing the current status of the hydrate operation",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"drySHA": {
+						SchemaProps: spec.SchemaProps{
+							Description: "DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"hydratedSHA": {
+						SchemaProps: spec.SchemaProps{
+							Description: "HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"sourceHydrator": {
+						SchemaProps: spec.SchemaProps{
+							Description: "SourceHydrator holds the hydrator config used for the hydrate operation",
+							Default:     map[string]interface{}{},
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator"),
+						},
+					},
+				},
+				Required: []string{"phase", "message"},
+			},
+		},
+		Dependencies: []string{
+			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator", "k8s.io/apimachinery/pkg/apis/meta/v1.Time"},
+	}
+}
+
+func schema_pkg_apis_application_v1alpha1_HydrateTo(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "HydrateTo specifies a location to which hydrated manifests should be pushed as a \"staging area\" before being moved to the SyncSource. The RepoURL and Path are assumed based on the associated SyncSource config in the SourceHydrator.",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"targetBranch": {
+						SchemaProps: spec.SchemaProps{
+							Description: "TargetBranch is the branch to which hydrated manifests should be committed",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+				},
+				Required: []string{"targetBranch"},
+			},
+		},
+	}
+}
+
 func schema_pkg_apis_application_v1alpha1_Info(ref common.ReferenceCallback) common.OpenAPIDefinition {
 	return common.OpenAPIDefinition{
 		Schema: spec.Schema{
@@ -7651,6 +7796,105 @@ func schema_pkg_apis_application_v1alpha1_SignatureKey(ref common.ReferenceCallb
 	}
 }
 
+func schema_pkg_apis_application_v1alpha1_SourceHydrator(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "SourceHydrator specifies a dry \"don't repeat yourself\" source for manifests, a sync source from which to sync hydrated manifests, and an optional hydrateTo location to act as a \"staging\" aread for hydrated manifests.",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"drySource": {
+						SchemaProps: spec.SchemaProps{
+							Description: "DrySource specifies where the dry \"don't repeat yourself\" manifest source lives.",
+							Default:     map[string]interface{}{},
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.DrySource"),
+						},
+					},
+					"syncSource": {
+						SchemaProps: spec.SchemaProps{
+							Description: "SyncSource specifies where to sync hydrated manifests from.",
+							Default:     map[string]interface{}{},
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncSource"),
+						},
+					},
+					"hydrateTo": {
+						SchemaProps: spec.SchemaProps{
+							Description: "HydrateTo specifies an optional \"staging\" location to push hydrated manifests to. An external system would then have to move manifests to the SyncSource, e.g. by pull request.",
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HydrateTo"),
+						},
+					},
+				},
+				Required: []string{"drySource", "syncSource"},
+			},
+		},
+		Dependencies: []string{
+			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.DrySource", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HydrateTo", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SyncSource"},
+	}
+}
+
+func schema_pkg_apis_application_v1alpha1_SourceHydratorStatus(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "SourceHydratorStatus contains information about the current state of source hydration",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"lastSuccessfulOperation": {
+						SchemaProps: spec.SchemaProps{
+							Description: "LastSuccessfulOperation holds info about the most recent successful hydration",
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SuccessfulHydrateOperation"),
+						},
+					},
+					"currentOperation": {
+						SchemaProps: spec.SchemaProps{
+							Description: "CurrentOperation holds the status of the hydrate operation",
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HydrateOperation"),
+						},
+					},
+				},
+			},
+		},
+		Dependencies: []string{
+			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.HydrateOperation", "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SuccessfulHydrateOperation"},
+	}
+}
+
+func schema_pkg_apis_application_v1alpha1_SuccessfulHydrateOperation(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "SuccessfulHydrateOperation contains information about the most recent successful hydrate operation",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"drySHA": {
+						SchemaProps: spec.SchemaProps{
+							Description: "DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"hydratedSHA": {
+						SchemaProps: spec.SchemaProps{
+							Description: "HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"sourceHydrator": {
+						SchemaProps: spec.SchemaProps{
+							Description: "SourceHydrator holds the hydrator config used for the hydrate operation",
+							Default:     map[string]interface{}{},
+							Ref:         ref("github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator"),
+						},
+					},
+				},
+			},
+		},
+		Dependencies: []string{
+			"github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1.SourceHydrator"},
+	}
+}
+
 func schema_pkg_apis_application_v1alpha1_SyncOperation(ref common.ReferenceCallback) common.OpenAPIDefinition {
 	return common.OpenAPIDefinition{
 		Schema: spec.Schema{
@@ -7973,6 +8217,36 @@ func schema_pkg_apis_application_v1alpha1_SyncPolicyAutomated(ref common.Referen
 	}
 }
 
+func schema_pkg_apis_application_v1alpha1_SyncSource(ref common.ReferenceCallback) common.OpenAPIDefinition {
+	return common.OpenAPIDefinition{
+		Schema: spec.Schema{
+			SchemaProps: spec.SchemaProps{
+				Description: "SyncSource specifies a location from which hydrated manifests may be synced. RepoURL is assumed based on the associated DrySource config in the SourceHydrator.",
+				Type:        []string{"object"},
+				Properties: map[string]spec.Schema{
+					"targetBranch": {
+						SchemaProps: spec.SchemaProps{
+							Description: "TargetBranch is the branch to which hydrated manifests should be committed",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+					"path": {
+						SchemaProps: spec.SchemaProps{
+							Description: "Path is a directory path within the git repository where hydrated manifests should be committed to and synced from. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.",
+							Default:     "",
+							Type:        []string{"string"},
+							Format:      "",
+						},
+					},
+				},
+				Required: []string{"targetBranch", "path"},
+			},
+		},
+	}
+}
+
 func schema_pkg_apis_application_v1alpha1_SyncStatus(ref common.ReferenceCallback) common.OpenAPIDefinition {
 	return common.OpenAPIDefinition{
 		Schema: spec.Schema{

pkg/apis/application/v1alpha1/types.go

@@ -86,6 +86,9 @@ type ApplicationSpec struct {
 
 	// Sources is a reference to the location of the application's manifests or chart
 	Sources ApplicationSources `json:"sources,omitempty" protobuf:"bytes,8,opt,name=sources"`
+
+	// SourceHydrator provides a way to push hydrated manifests back to git before syncing them to the cluster.
+	SourceHydrator *SourceHydrator `json:"sourceHydrator,omitempty" protobuf:"bytes,9,opt,name=sourceHydrator"`
 }
 
 type IgnoreDifferences []ResourceIgnoreDifferences
@@ -216,6 +219,9 @@ func (a ApplicationSources) IsZero() bool {
 }
 
 func (a *ApplicationSpec) GetSource() ApplicationSource {
+	if a.SourceHydrator != nil {
+		return a.SourceHydrator.GetSyncSource()
+	}
 	// if Application has multiple sources, return the first source in sources
 	if a.HasMultipleSources() {
 		return a.Sources[0]
@@ -226,7 +232,26 @@ func (a *ApplicationSpec) GetSource() ApplicationSource {
 	return ApplicationSource{}
 }
 
+// GetHydrateToSource returns the hydrateTo source if it exists, otherwise returns the sync source.
+func (a *ApplicationSpec) GetHydrateToSource() ApplicationSource {
+	if a.SourceHydrator != nil {
+		targetRevision := a.SourceHydrator.SyncSource.TargetBranch
+		if a.SourceHydrator.HydrateTo != nil {
+			targetRevision = a.SourceHydrator.HydrateTo.TargetBranch
+		}
+		return ApplicationSource{
+			RepoURL:        a.SourceHydrator.DrySource.RepoURL,
+			Path:           a.SourceHydrator.SyncSource.Path,
+			TargetRevision: targetRevision,
+		}
+	}
+	return ApplicationSource{}
+}
+
 func (a *ApplicationSpec) GetSources() ApplicationSources {
+	if a.SourceHydrator != nil {
+		return ApplicationSources{a.SourceHydrator.GetSyncSource()}
+	}
 	if a.HasMultipleSources() {
 		return a.Sources
 	}
@@ -237,7 +262,7 @@ func (a *ApplicationSpec) GetSources() ApplicationSources {
 }
 
 func (a *ApplicationSpec) HasMultipleSources() bool {
-	return len(a.Sources) > 0
+	return a.SourceHydrator == nil && len(a.Sources) > 0
 }
 
 func (a *ApplicationSpec) GetSourcePtrByPosition(sourcePosition int) *ApplicationSource {
@@ -246,6 +271,10 @@ func (a *ApplicationSpec) GetSourcePtrByPosition(sourcePosition int) *Applicatio
 }
 
 func (a *ApplicationSpec) GetSourcePtrByIndex(sourceIndex int) *ApplicationSource {
+	if a.SourceHydrator != nil {
+		source := a.SourceHydrator.GetSyncSource()
+		return &source
+	}
 	// if Application has multiple sources, return the first source in sources
 	if a.HasMultipleSources() {
 		if sourceIndex > 0 {
@@ -351,6 +380,82 @@ const (
 	ApplicationSourceTypePlugin    ApplicationSourceType = "Plugin"
 )
 
+// SourceHydrator specifies a dry "don't repeat yourself" source for manifests, a sync source from which to sync
+// hydrated manifests, and an optional hydrateTo location to act as a "staging" aread for hydrated manifests.
+type SourceHydrator struct {
+	// DrySource specifies where the dry "don't repeat yourself" manifest source lives.
+	DrySource DrySource `json:"drySource" protobuf:"bytes,1,name=drySource"`
+	// SyncSource specifies where to sync hydrated manifests from.
+	SyncSource SyncSource `json:"syncSource" protobuf:"bytes,2,name=syncSource"`
+	// HydrateTo specifies an optional "staging" location to push hydrated manifests to. An external system would then
+	// have to move manifests to the SyncSource, e.g. by pull request.
+	HydrateTo *HydrateTo `json:"hydrateTo,omitempty" protobuf:"bytes,3,opt,name=hydrateTo"`
+}
+
+// GetSyncSource gets the source from which we should sync when a source hydrator is configured.
+func (s SourceHydrator) GetSyncSource() ApplicationSource {
+	return ApplicationSource{
+		// Pull the RepoURL from the dry source. The SyncSource's RepoURL is assumed to be the same.
+		RepoURL:        s.DrySource.RepoURL,
+		Path:           s.SyncSource.Path,
+		TargetRevision: s.SyncSource.TargetBranch,
+	}
+}
+
+// GetDrySource gets the dry source when a source hydrator is configured.
+func (s SourceHydrator) GetDrySource() ApplicationSource {
+	return ApplicationSource{
+		RepoURL:        s.DrySource.RepoURL,
+		Path:           s.DrySource.Path,
+		TargetRevision: s.DrySource.TargetRevision,
+	}
+}
+
+// DeepEquals returns true if the SourceHydrator is deeply equal to the given SourceHydrator.
+func (s SourceHydrator) DeepEquals(hydrator SourceHydrator) bool {
+	return s.DrySource == hydrator.DrySource && s.SyncSource == hydrator.SyncSource && s.HydrateTo.DeepEquals(hydrator.HydrateTo)
+}
+
+// DrySource specifies a location for dry "don't repeat yourself" manifest source information.
+type DrySource struct {
+	// RepoURL is the URL to the git repository that contains the application manifests
+	RepoURL string `json:"repoURL" protobuf:"bytes,1,name=repoURL"`
+	// TargetRevision defines the revision of the source to hydrate
+	TargetRevision string `json:"targetRevision" protobuf:"bytes,2,name=targetRevision"`
+	// Path is a directory path within the Git repository where the manifests are located
+	Path string `json:"path" protobuf:"bytes,3,name=path"`
+}
+
+// SyncSource specifies a location from which hydrated manifests may be synced. RepoURL is assumed based on the
+// associated DrySource config in the SourceHydrator.
+type SyncSource struct {
+	// TargetBranch is the branch to which hydrated manifests should be committed
+	TargetBranch string `json:"targetBranch" protobuf:"bytes,1,name=targetBranch"`
+	// Path is a directory path within the git repository where hydrated manifests should be committed to and synced
+	// from. If hydrateTo is set, this is just the path from which hydrated manifests will be synced.
+	Path string `json:"path" protobuf:"bytes,2,name=path"`
+}
+
+// HydrateTo specifies a location to which hydrated manifests should be pushed as a "staging area" before being moved to
+// the SyncSource. The RepoURL and Path are assumed based on the associated SyncSource config in the SourceHydrator.
+type HydrateTo struct {
+	// TargetBranch is the branch to which hydrated manifests should be committed
+	TargetBranch string `json:"targetBranch" protobuf:"bytes,1,name=targetBranch"`
+}
+
+// DeepEquals returns true if the HydrateTo is deeply equal to the given HydrateTo.
+func (in *HydrateTo) DeepEquals(to *HydrateTo) bool {
+	if in == nil {
+		return to == nil
+	}
+	if to == nil {
+		// We already know in is not nil.
+		return false
+	}
+	// Compare de-referenced structs.
+	return *in == *to
+}
+
 // RefreshType specifies how to refresh the sources of a given application
 type RefreshType string
 
@@ -1051,6 +1156,16 @@ type ApplicationStatus struct {
 	SourceTypes []ApplicationSourceType `json:"sourceTypes,omitempty" protobuf:"bytes,12,opt,name=sourceTypes"`
 	// ControllerNamespace indicates the namespace in which the application controller is located
 	ControllerNamespace string `json:"controllerNamespace,omitempty" protobuf:"bytes,13,opt,name=controllerNamespace"`
+	// SourceHydrator stores information about the current state of source hydration
+	SourceHydrator SourceHydratorStatus `json:"sourceHydrator,omitempty" protobuf:"bytes,14,opt,name=sourceHydrator"`
+}
+
+// SourceHydratorStatus contains information about the current state of source hydration
+type SourceHydratorStatus struct {
+	// LastSuccessfulOperation holds info about the most recent successful hydration
+	LastSuccessfulOperation *SuccessfulHydrateOperation `json:"lastSuccessfulOperation,omitempty" protobuf:"bytes,1,opt,name=lastSuccessfulOperation"`
+	// CurrentOperation holds the status of the hydrate operation
+	CurrentOperation *HydrateOperation `json:"currentOperation,omitempty" protobuf:"bytes,2,opt,name=currentOperation"`
 }
 
 func (a *ApplicationStatus) FindResource(key kube.ResourceKey) (*ResourceStatus, bool) {
@@ -1063,6 +1178,44 @@ func (a *ApplicationStatus) FindResource(key kube.ResourceKey) (*ResourceStatus,
 	return nil, false
 }
 
+// HydrateOperation contains information about the most recent hydrate operation
+type HydrateOperation struct {
+	// StartedAt indicates when the hydrate operation started
+	StartedAt metav1.Time `json:"startedAt,omitempty" protobuf:"bytes,1,opt,name=startedAt"`
+	// FinishedAt indicates when the hydrate operation finished
+	FinishedAt *metav1.Time `json:"finishedAt,omitempty" protobuf:"bytes,2,opt,name=finishedAt"`
+	// Phase indicates the status of the hydrate operation
+	Phase HydrateOperationPhase `json:"phase" protobuf:"bytes,3,opt,name=phase"`
+	// Message contains a message describing the current status of the hydrate operation
+	Message string `json:"message" protobuf:"bytes,4,opt,name=message"`
+	// DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation
+	DrySHA string `json:"drySHA,omitempty" protobuf:"bytes,5,opt,name=drySHA"`
+	// HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation
+	HydratedSHA string `json:"hydratedSHA,omitempty" protobuf:"bytes,6,opt,name=hydratedSHA"`
+	// SourceHydrator holds the hydrator config used for the hydrate operation
+	SourceHydrator SourceHydrator `json:"sourceHydrator,omitempty" protobuf:"bytes,7,opt,name=sourceHydrator"`
+}
+
+// SuccessfulHydrateOperation contains information about the most recent successful hydrate operation
+type SuccessfulHydrateOperation struct {
+	// DrySHA holds the resolved revision (sha) of the dry source as of the most recent reconciliation
+	DrySHA string `json:"drySHA,omitempty" protobuf:"bytes,5,opt,name=drySHA"`
+	// HydratedSHA holds the resolved revision (sha) of the hydrated source as of the most recent reconciliation
+	HydratedSHA string `json:"hydratedSHA,omitempty" protobuf:"bytes,6,opt,name=hydratedSHA"`
+	// SourceHydrator holds the hydrator config used for the hydrate operation
+	SourceHydrator SourceHydrator `json:"sourceHydrator,omitempty" protobuf:"bytes,7,opt,name=sourceHydrator"`
+}
+
+// HydrateOperationPhase indicates the status of a hydrate operation
+// +kubebuilder:validation:Enum=Hydrating;Failed;Hydrated
+type HydrateOperationPhase string
+
+const (
+	HydrateOperationPhaseHydrating HydrateOperationPhase = "Hydrating"
+	HydrateOperationPhaseFailed    HydrateOperationPhase = "Failed"
+	HydrateOperationPhaseHydrated  HydrateOperationPhase = "Hydrated"
+)
+
 // GetRevisions will return the current revision associated with the Application.
 // If app has multisources, it will return all corresponding revisions preserving
 // order from the app.spec.sources. If app has only one source, it will return a
@@ -2863,6 +3016,22 @@ func (app *Application) IsRefreshRequested() (RefreshType, bool) {
 	return refreshType, true
 }
 
+// IsHydrateRequested returns whether hydration has been requested for an application
+func (app *Application) IsHydrateRequested() bool {
+	annotations := app.GetAnnotations()
+	if annotations == nil {
+		return false
+	}
+	typeStr, ok := annotations[AnnotationKeyHydrate]
+	if !ok {
+		return false
+	}
+	if typeStr == "normal" {
+		return true
+	}
+	return false
+}
+
 func (app *Application) HasPostDeleteFinalizer(stage ...string) bool {
 	return getFinalizerIndex(app.ObjectMeta, strings.Join(append([]string{PostDeleteFinalizerName}, stage...), "/")) > -1
 }

pkg/apis/application/v1alpha1/zz_generated.deepcopy.go

@@ -1352,6 +1352,11 @@ func (in *ApplicationSpec) DeepCopyInto(out *ApplicationSpec) {
 			(*in)[i].DeepCopyInto(&(*out)[i])
 		}
 	}
+	if in.SourceHydrator != nil {
+		in, out := &in.SourceHydrator, &out.SourceHydrator
+		*out = new(SourceHydrator)
+		(*in).DeepCopyInto(*out)
+	}
 	return
 }
 
@@ -1410,6 +1415,7 @@ func (in *ApplicationStatus) DeepCopyInto(out *ApplicationStatus) {
 		*out = make([]ApplicationSourceType, len(*in))
 		copy(*out, *in)
 	}
+	in.SourceHydrator.DeepCopyInto(&out.SourceHydrator)
 	return
 }
 
@@ -1906,6 +1912,22 @@ func (in *ConnectionState) DeepCopy() *ConnectionState {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *DrySource) DeepCopyInto(out *DrySource) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new DrySource.
+func (in *DrySource) DeepCopy() *DrySource {
+	if in == nil {
+		return nil
+	}
+	out := new(DrySource)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *DuckTypeGenerator) DeepCopyInto(out *DuckTypeGenerator) {
 	*out = *in
@@ -2242,6 +2264,44 @@ func (in *HostResourceInfo) DeepCopy() *HostResourceInfo {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *HydrateOperation) DeepCopyInto(out *HydrateOperation) {
+	*out = *in
+	in.StartedAt.DeepCopyInto(&out.StartedAt)
+	if in.FinishedAt != nil {
+		in, out := &in.FinishedAt, &out.FinishedAt
+		*out = (*in).DeepCopy()
+	}
+	in.SourceHydrator.DeepCopyInto(&out.SourceHydrator)
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new HydrateOperation.
+func (in *HydrateOperation) DeepCopy() *HydrateOperation {
+	if in == nil {
+		return nil
+	}
+	out := new(HydrateOperation)
+	in.DeepCopyInto(out)
+	return out
+}
+
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *HydrateTo) DeepCopyInto(out *HydrateTo) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new HydrateTo.
+func (in *HydrateTo) DeepCopy() *HydrateTo {
+	if in == nil {
+		return nil
+	}
+	out := new(HydrateTo)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in IgnoreDifferences) DeepCopyInto(out *IgnoreDifferences) {
 	{
@@ -4193,6 +4253,72 @@ func (in *SignatureKey) DeepCopy() *SignatureKey {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *SourceHydrator) DeepCopyInto(out *SourceHydrator) {
+	*out = *in
+	out.DrySource = in.DrySource
+	out.SyncSource = in.SyncSource
+	if in.HydrateTo != nil {
+		in, out := &in.HydrateTo, &out.HydrateTo
+		*out = new(HydrateTo)
+		**out = **in
+	}
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new SourceHydrator.
+func (in *SourceHydrator) DeepCopy() *SourceHydrator {
+	if in == nil {
+		return nil
+	}
+	out := new(SourceHydrator)
+	in.DeepCopyInto(out)
+	return out
+}
+
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *SourceHydratorStatus) DeepCopyInto(out *SourceHydratorStatus) {
+	*out = *in
+	if in.LastSuccessfulOperation != nil {
+		in, out := &in.LastSuccessfulOperation, &out.LastSuccessfulOperation
+		*out = new(SuccessfulHydrateOperation)
+		(*in).DeepCopyInto(*out)
+	}
+	if in.CurrentOperation != nil {
+		in, out := &in.CurrentOperation, &out.CurrentOperation
+		*out = new(HydrateOperation)
+		(*in).DeepCopyInto(*out)
+	}
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new SourceHydratorStatus.
+func (in *SourceHydratorStatus) DeepCopy() *SourceHydratorStatus {
+	if in == nil {
+		return nil
+	}
+	out := new(SourceHydratorStatus)
+	in.DeepCopyInto(out)
+	return out
+}
+
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *SuccessfulHydrateOperation) DeepCopyInto(out *SuccessfulHydrateOperation) {
+	*out = *in
+	in.SourceHydrator.DeepCopyInto(&out.SourceHydrator)
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new SuccessfulHydrateOperation.
+func (in *SuccessfulHydrateOperation) DeepCopy() *SuccessfulHydrateOperation {
+	if in == nil {
+		return nil
+	}
+	out := new(SuccessfulHydrateOperation)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *SyncOperation) DeepCopyInto(out *SyncOperation) {
 	*out = *in
@@ -4379,6 +4505,22 @@ func (in *SyncPolicyAutomated) DeepCopy() *SyncPolicyAutomated {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *SyncSource) DeepCopyInto(out *SyncSource) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new SyncSource.
+func (in *SyncSource) DeepCopy() *SyncSource {
+	if in == nil {
+		return nil
+	}
+	out := new(SyncSource)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *SyncStatus) DeepCopyInto(out *SyncStatus) {
 	*out = *in

pkg/ratelimiter/ratelimiter.go

@@ -35,10 +35,10 @@ func GetDefaultAppRateLimiterConfig() *AppControllerRateLimiterConfig {
 
 // NewCustomAppControllerRateLimiter is a constructor for the rate limiter for a workqueue used by app controller.  It has
 // both overall and per-item rate limiting.  The overall is a token bucket and the per-item is exponential(with auto resets)
-func NewCustomAppControllerRateLimiter(cfg *AppControllerRateLimiterConfig) workqueue.TypedRateLimiter[string] {
-	return workqueue.NewTypedMaxOfRateLimiter[string](
-		NewItemExponentialRateLimiterWithAutoReset(cfg.BaseDelay, cfg.MaxDelay, cfg.FailureCoolDown, cfg.BackoffFactor),
-		&workqueue.TypedBucketRateLimiter[string]{Limiter: rate.NewLimiter(rate.Limit(cfg.BucketQPS), int(cfg.BucketSize))},
+func NewCustomAppControllerRateLimiter[T comparable](cfg *AppControllerRateLimiterConfig) workqueue.TypedRateLimiter[T] {
+	return workqueue.NewTypedMaxOfRateLimiter[T](
+		NewItemExponentialRateLimiterWithAutoReset[T](cfg.BaseDelay, cfg.MaxDelay, cfg.FailureCoolDown, cfg.BackoffFactor),
+		&workqueue.TypedBucketRateLimiter[T]{Limiter: rate.NewLimiter(rate.Limit(cfg.BucketQPS), int(cfg.BucketSize))},
 	)
 }
 
@@ -49,7 +49,7 @@ type failureData struct {
 
 // ItemExponentialRateLimiterWithAutoReset does a simple baseDelay*2^<num-failures> limit
 // dealing with max failures and expiration/resets are up dependent on the cooldown period
-type ItemExponentialRateLimiterWithAutoReset struct {
+type ItemExponentialRateLimiterWithAutoReset[T comparable] struct {
 	failuresLock sync.Mutex
 	failures     map[interface{}]failureData
 
@@ -59,10 +59,10 @@ type ItemExponentialRateLimiterWithAutoReset struct {
 	backoffFactor float64
 }
 
-var _ workqueue.TypedRateLimiter[string] = &ItemExponentialRateLimiterWithAutoReset{}
+var _ workqueue.TypedRateLimiter[string] = &ItemExponentialRateLimiterWithAutoReset[string]{}
 
-func NewItemExponentialRateLimiterWithAutoReset(baseDelay, maxDelay, failureCoolDown time.Duration, backoffFactor float64) workqueue.TypedRateLimiter[string] {
-	return &ItemExponentialRateLimiterWithAutoReset{
+func NewItemExponentialRateLimiterWithAutoReset[T comparable](baseDelay, maxDelay, failureCoolDown time.Duration, backoffFactor float64) workqueue.TypedRateLimiter[T] {
+	return &ItemExponentialRateLimiterWithAutoReset[T]{
 		failures:      map[interface{}]failureData{},
 		baseDelay:     baseDelay,
 		maxDelay:      maxDelay,
@@ -71,7 +71,7 @@ func NewItemExponentialRateLimiterWithAutoReset(baseDelay, maxDelay, failureCool
 	}
 }
 
-func (r *ItemExponentialRateLimiterWithAutoReset) When(item string) time.Duration {
+func (r *ItemExponentialRateLimiterWithAutoReset[T]) When(item T) time.Duration {
 	r.failuresLock.Lock()
 	defer r.failuresLock.Unlock()
 
@@ -109,14 +109,14 @@ func (r *ItemExponentialRateLimiterWithAutoReset) When(item string) time.Duratio
 	return calculated
 }
 
-func (r *ItemExponentialRateLimiterWithAutoReset) NumRequeues(item string) int {
+func (r *ItemExponentialRateLimiterWithAutoReset[T]) NumRequeues(item T) int {
 	r.failuresLock.Lock()
 	defer r.failuresLock.Unlock()
 
 	return r.failures[item].failures
 }
 
-func (r *ItemExponentialRateLimiterWithAutoReset) Forget(item string) {
+func (r *ItemExponentialRateLimiterWithAutoReset[T]) Forget(item T) {
 	r.failuresLock.Lock()
 	defer r.failuresLock.Unlock()
 

reposerver/repository/repository.go

@@ -1138,6 +1138,9 @@ func helmTemplate(appPath string, repoRoot string, env *v1alpha1.Env, q *apiclie
 		if appHelm.ReleaseName != "" {
 			templateOpts.Name = appHelm.ReleaseName
 		}
+		if appHelm.Namespace != "" {
+			templateOpts.Namespace = appHelm.Namespace
+		}
 
 		resolvedValueFiles, err := getResolvedValueFiles(appPath, repoRoot, env, q.GetValuesFileSchemes(), appHelm.ValueFiles, q.RefSources, gitRepoPaths, appHelm.IgnoreMissingValueFiles)
 		if err != nil {
@@ -2529,7 +2532,7 @@ func checkoutRevision(gitClient git.Client, revision string, submoduleEnabled bo
 		}
 	}
 
-	err = gitClient.Checkout(revision, submoduleEnabled)
+	_, err = gitClient.Checkout(revision, submoduleEnabled)
 	if err != nil {
 		// When fetching with no revision, only refs/heads/* and refs/remotes/origin/* are fetched. If checkout fails
 		// for the given revision, try explicitly fetching it.
@@ -2541,7 +2544,7 @@ func checkoutRevision(gitClient git.Client, revision string, submoduleEnabled bo
 			return status.Errorf(codes.Internal, "Failed to checkout revision %s: %v", revision, err)
 		}
 
-		err = gitClient.Checkout("FETCH_HEAD", submoduleEnabled)
+		_, err = gitClient.Checkout("FETCH_HEAD", submoduleEnabled)
 		if err != nil {
 			return status.Errorf(codes.Internal, "Failed to checkout FETCH_HEAD: %v", err)
 		}

reposerver/repository/repository_test.go

@@ -109,7 +109,7 @@ func newServiceWithMocks(t *testing.T, root string, signed bool) (*Service, *git
 		gitClient.On("Init").Return(nil)
 		gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 		gitClient.On("Fetch", mock.Anything).Return(nil)
-		gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+		gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 		gitClient.On("LsRemote", mock.Anything).Return(mock.Anything, nil)
 		gitClient.On("CommitSHA").Return(mock.Anything, nil)
 		gitClient.On("Root").Return(root)
@@ -188,7 +188,7 @@ func newServiceWithCommitSHA(t *testing.T, root, revision string) *Service {
 		gitClient.On("Init").Return(nil)
 		gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 		gitClient.On("Fetch", mock.Anything).Return(nil)
-		gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+		gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 		gitClient.On("LsRemote", revision).Return(revision, revisionErr)
 		gitClient.On("CommitSHA").Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 		gitClient.On("Root").Return(root)
@@ -3071,7 +3071,7 @@ func TestCheckoutRevisionPresentSkipFetch(t *testing.T) {
 	gitClient := &gitmocks.Client{}
 	gitClient.On("Init").Return(nil)
 	gitClient.On("IsRevisionPresent", revision).Return(true)
-	gitClient.On("Checkout", revision, mock.Anything).Return(nil)
+	gitClient.On("Checkout", revision, mock.Anything).Return("", nil)
 
 	err := checkoutRevision(gitClient, revision, false)
 	require.NoError(t, err)
@@ -3084,7 +3084,7 @@ func TestCheckoutRevisionNotPresentCallFetch(t *testing.T) {
 	gitClient.On("Init").Return(nil)
 	gitClient.On("IsRevisionPresent", revision).Return(false)
 	gitClient.On("Fetch", "").Return(nil)
-	gitClient.On("Checkout", revision, mock.Anything).Return(nil)
+	gitClient.On("Checkout", revision, mock.Anything).Return("", nil)
 
 	err := checkoutRevision(gitClient, revision, false)
 	require.NoError(t, err)
@@ -3410,7 +3410,7 @@ func TestErrorGetGitDirectories(t *testing.T) {
 		}, want: nil, wantErr: assert.Error},
 		{name: "InvalidResolveRevision", fields: fields{service: func() *Service {
 			s, _, _ := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", mock.Anything).Return("", fmt.Errorf("ah error"))
 				gitClient.On("Root").Return(root)
 				paths.On("GetPath", mock.Anything).Return(".", nil)
@@ -3427,7 +3427,7 @@ func TestErrorGetGitDirectories(t *testing.T) {
 		}, want: nil, wantErr: assert.Error},
 		{name: "ErrorVerifyCommit", fields: fields{service: func() *Service {
 			s, _, _ := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", mock.Anything).Return("", fmt.Errorf("ah error"))
 				gitClient.On("VerifyCommitSignature", mock.Anything).Return("", fmt.Errorf("revision %s is not signed", "sadfsadf"))
 				gitClient.On("Root").Return(root)
@@ -3464,7 +3464,7 @@ func TestGetGitDirectories(t *testing.T) {
 		gitClient.On("Init").Return(nil)
 		gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 		gitClient.On("Fetch", mock.Anything).Return(nil)
-		gitClient.On("Checkout", mock.Anything, mock.Anything).Once().Return(nil)
+		gitClient.On("Checkout", mock.Anything, mock.Anything).Once().Return("", nil)
 		gitClient.On("LsRemote", "HEAD").Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 		gitClient.On("Root").Return(root)
 		paths.On("GetPath", mock.Anything).Return(root, nil)
@@ -3497,7 +3497,7 @@ func TestGetGitDirectoriesWithHiddenDirSupported(t *testing.T) {
 		gitClient.On("Init").Return(nil)
 		gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 		gitClient.On("Fetch", mock.Anything).Return(nil)
-		gitClient.On("Checkout", mock.Anything, mock.Anything).Once().Return(nil)
+		gitClient.On("Checkout", mock.Anything, mock.Anything).Once().Return("", nil)
 		gitClient.On("LsRemote", "HEAD").Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 		gitClient.On("Root").Return(root)
 		paths.On("GetPath", mock.Anything).Return(root, nil)
@@ -3552,7 +3552,7 @@ func TestErrorGetGitFiles(t *testing.T) {
 		}, want: nil, wantErr: assert.Error},
 		{name: "InvalidResolveRevision", fields: fields{service: func() *Service {
 			s, _, _ := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", mock.Anything).Return("", fmt.Errorf("ah error"))
 				gitClient.On("Root").Return(root)
 				paths.On("GetPath", mock.Anything).Return(".", nil)
@@ -3591,7 +3591,7 @@ func TestGetGitFiles(t *testing.T) {
 		gitClient.On("Init").Return(nil)
 		gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 		gitClient.On("Fetch", mock.Anything).Return(nil)
-		gitClient.On("Checkout", mock.Anything, mock.Anything).Once().Return(nil)
+		gitClient.On("Checkout", mock.Anything, mock.Anything).Once().Return("", nil)
 		gitClient.On("LsRemote", "HEAD").Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 		gitClient.On("Root").Return(root)
 		gitClient.On("LsFiles", mock.Anything, mock.Anything).Once().Return(files, nil)
@@ -3655,7 +3655,7 @@ func TestErrorUpdateRevisionForPaths(t *testing.T) {
 		}, want: nil, wantErr: assert.Error},
 		{name: "InvalidResolveRevision", fields: fields{service: func() *Service {
 			s, _, _ := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", mock.Anything).Return("", fmt.Errorf("ah error"))
 				gitClient.On("Root").Return(root)
 				paths.On("GetPath", mock.Anything).Return(".", nil)
@@ -3673,7 +3673,7 @@ func TestErrorUpdateRevisionForPaths(t *testing.T) {
 		}, want: nil, wantErr: assert.Error},
 		{name: "InvalidResolveSyncedRevision", fields: fields{service: func() *Service {
 			s, _, _ := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", "HEAD").Once().Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 				gitClient.On("LsRemote", mock.Anything).Return("", fmt.Errorf("ah error"))
 				gitClient.On("Root").Return(root)
@@ -3726,7 +3726,7 @@ func TestUpdateRevisionForPaths(t *testing.T) {
 	}{
 		{name: "NoPathAbort", fields: func() fields {
 			s, _, c := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 			}, ".")
 			return fields{
 				service: s,
@@ -3741,7 +3741,7 @@ func TestUpdateRevisionForPaths(t *testing.T) {
 		}, want: &apiclient.UpdateRevisionForPathsResponse{}, wantErr: assert.NoError},
 		{name: "SameResolvedRevisionAbort", fields: func() fields {
 			s, _, c := newServiceWithOpt(t, func(gitClient *gitmocks.Client, helmClient *helmmocks.Client, paths *iomocks.TempPaths) {
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", "HEAD").Once().Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 				gitClient.On("LsRemote", "SYNCEDHEAD").Once().Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 				paths.On("GetPath", mock.Anything).Return(".", nil)
@@ -3767,7 +3767,7 @@ func TestUpdateRevisionForPaths(t *testing.T) {
 				gitClient.On("Init").Return(nil)
 				gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 				gitClient.On("Fetch", mock.Anything).Return(nil)
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", "HEAD").Once().Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 				gitClient.On("LsRemote", "SYNCEDHEAD").Once().Return("1e67a504d03def3a6a1125d934cb511680f72555", nil)
 				paths.On("GetPath", mock.Anything).Return(".", nil)
@@ -3796,7 +3796,7 @@ func TestUpdateRevisionForPaths(t *testing.T) {
 				gitClient.On("Init").Return(nil)
 				gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 				gitClient.On("Fetch", mock.Anything).Return(nil)
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", "HEAD").Once().Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 				gitClient.On("LsRemote", "SYNCEDHEAD").Once().Return("1e67a504d03def3a6a1125d934cb511680f72555", nil)
 				paths.On("GetPath", mock.Anything).Return(".", nil)
@@ -3834,7 +3834,7 @@ func TestUpdateRevisionForPaths(t *testing.T) {
 				gitClient.On("Init").Return(nil)
 				gitClient.On("IsRevisionPresent", mock.Anything).Return(false)
 				gitClient.On("Fetch", mock.Anything).Return(nil)
-				gitClient.On("Checkout", mock.Anything, mock.Anything).Return(nil)
+				gitClient.On("Checkout", mock.Anything, mock.Anything).Return("", nil)
 				gitClient.On("LsRemote", "HEAD").Once().Return("632039659e542ed7de0c170a4fcc1c571b288fc0", nil)
 				gitClient.On("LsRemote", "SYNCEDHEAD").Once().Return("1e67a504d03def3a6a1125d934cb511680f72555", nil)
 				paths.On("GetPath", mock.Anything).Return(".", nil)

server/application/application_test.go

@@ -109,7 +109,7 @@ func fakeResolveRevisionResponseHelm() *apiclient.ResolveRevisionResponse {
 
 func fakeRepoServerClient(isHelm bool) *mocks.RepoServerServiceClient {
 	mockRepoServiceClient := mocks.RepoServerServiceClient{}
-	mockRepoServiceClient.On("ListApps", mock.Anything, mock.Anything).Return(fakeAppList(), nil)
+	mockRepoServiceClient.On("GetProcessableApps", mock.Anything, mock.Anything).Return(fakeAppList(), nil)
 	mockRepoServiceClient.On("GenerateManifest", mock.Anything, mock.Anything).Return(&apiclient.ManifestResponse{}, nil)
 	mockRepoServiceClient.On("GetAppDetails", mock.Anything, mock.Anything).Return(&apiclient.RepoAppDetailsResponse{}, nil)
 	mockRepoServiceClient.On("TestRepository", mock.Anything, mock.Anything).Return(&apiclient.TestRepositoryResponse{}, nil)

server/repository/repository_test.go

@@ -555,7 +555,7 @@ func TestRepositoryServerListApps(t *testing.T) {
 			AppProject: "default",
 		})
 		require.NoError(t, err)
-		assert.Len(t, resp.Items, 1)
+		require.Len(t, resp.Items, 1)
 		assert.Equal(t, "path/to/dir", resp.Items[0].Path)
 		assert.Equal(t, "Kustomize", resp.Items[0].Type)
 	})

test/container/Procfile

@@ -3,6 +3,7 @@ api-server: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run
 dex: sh -c "test $ARGOCD_IN_CI = true && exit 0; ARGOCD_BINARY_NAME=argocd-dex go run github.com/argoproj/argo-cd/cmd gendexcfg -o `pwd`/dist/dex.yaml && docker run --rm -p ${ARGOCD_E2E_DEX_PORT:-5556}:${ARGOCD_E2E_DEX_PORT:-5556} -v `pwd`/dist/dex.yaml:/dex.yaml ghcr.io/dexidp/dex:v2.41.1 serve /dex.yaml"
 redis: sh -c "/usr/local/bin/redis-server --save "" --appendonly no --port ${ARGOCD_E2E_REDIS_PORT:-6379}"
 repo-server: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "FORCE_LOG_COLORS=1 ARGOCD_FAKE_IN_CLUSTER=true ARGOCD_GNUPGHOME=${ARGOCD_GNUPGHOME:-/tmp/argocd-local/gpg/keys} ARGOCD_PLUGINSOCKFILEPATH=${ARGOCD_PLUGINSOCKFILEPATH:-./test/cmp}  ARGOCD_GPG_DATA_PATH=${ARGOCD_GPG_DATA_PATH:-/tmp/argocd-local/gpg/source} ARGOCD_BINARY_NAME=argocd-repo-server $COMMAND --loglevel debug --port ${ARGOCD_E2E_REPOSERVER_PORT:-8081} --redis localhost:${ARGOCD_E2E_REDIS_PORT:-6379}"
+commit-server: [ "$BIN_MODE" = 'true' ] && COMMAND=./dist/argocd || COMMAND='go run ./cmd/main.go' && sh -c "FORCE_LOG_COLORS=1 ARGOCD_BINARY_NAME=argocd-commit-server $COMMAND --loglevel debug --port ${ARGOCD_E2E_COMMITSERVER_PORT:-8086}"
 ui: sh -c "test $ARGOCD_IN_CI = true && exit 0; cd ui && ARGOCD_E2E_YARN_HOST=0.0.0.0 ${ARGOCD_E2E_YARN_CMD:-yarn} start"
 reaper: ./test/container/reaper.sh
 sshd: sudo sh -c "test $ARGOCD_E2E_TEST = true && /usr/sbin/sshd -p 2222 -D -e"

test/e2e/fixture/app/actions.go

@@ -224,9 +224,14 @@ func (a *Actions) prepareCreateAppArgs(args []string) []string {
 	a.context.t.Helper()
 	args = append([]string{
 		"app", "create", a.context.AppQualifiedName(),
-		"--repo", fixture.RepoURL(a.context.repoURLType),
 	}, args...)
 
+	if a.context.drySourceRevision != "" || a.context.drySourcePath != "" || a.context.syncSourcePath != "" || a.context.syncSourceBranch != "" || a.context.hydrateToBranch != "" {
+		args = append(args, "--dry-source-repo", fixture.RepoURL(a.context.repoURLType))
+	} else {
+		args = append(args, "--repo", fixture.RepoURL(a.context.repoURLType))
+	}
+
 	if a.context.destName != "" && a.context.isDestServerInferred && !slices.Contains(args, "--dest-server") {
 		args = append(args, "--dest-name", a.context.destName)
 	} else {
@@ -236,6 +241,26 @@ func (a *Actions) prepareCreateAppArgs(args []string) []string {
 		args = append(args, "--path", a.context.path)
 	}
 
+	if a.context.drySourceRevision != "" {
+		args = append(args, "--dry-source-revision", a.context.drySourceRevision)
+	}
+
+	if a.context.drySourcePath != "" {
+		args = append(args, "--dry-source-path", a.context.drySourcePath)
+	}
+
+	if a.context.syncSourceBranch != "" {
+		args = append(args, "--sync-source-branch", a.context.syncSourceBranch)
+	}
+
+	if a.context.syncSourcePath != "" {
+		args = append(args, "--sync-source-path", a.context.syncSourcePath)
+	}
+
+	if a.context.hydrateToBranch != "" {
+		args = append(args, "--hydrate-to-branch", a.context.hydrateToBranch)
+	}
+
 	if a.context.chart != "" {
 		args = append(args, "--helm-chart", a.context.chart)
 	}

test/e2e/fixture/app/context.go

@@ -49,6 +49,11 @@ type Context struct {
 	helmSkipTests            bool
 	trackingMethod           v1alpha1.TrackingMethod
 	sources                  []v1alpha1.ApplicationSource
+	drySourceRevision        string
+	drySourcePath            string
+	syncSourceBranch         string
+	syncSourcePath           string
+	hydrateToBranch          string
 }
 
 type ContextArgs struct {
@@ -243,6 +248,31 @@ func (c *Context) Path(path string) *Context {
 	return c
 }
 
+func (c *Context) DrySourceRevision(revision string) *Context {
+	c.drySourceRevision = revision
+	return c
+}
+
+func (c *Context) DrySourcePath(path string) *Context {
+	c.drySourcePath = path
+	return c
+}
+
+func (c *Context) SyncSourceBranch(branch string) *Context {
+	c.syncSourceBranch = branch
+	return c
+}
+
+func (c *Context) SyncSourcePath(path string) *Context {
+	c.syncSourcePath = path
+	return c
+}
+
+func (c *Context) HydrateToBranch(branch string) *Context {
+	c.hydrateToBranch = branch
+	return c
+}
+
 func (c *Context) Recurse() *Context {
 	c.directoryRecurse = true
 	return c

test/e2e/hydrator_test.go

@@ -0,0 +1,102 @@
+package e2e
+
+import (
+	"testing"
+
+	. "github.com/argoproj/argo-cd/v2/pkg/apis/application/v1alpha1"
+	. "github.com/argoproj/argo-cd/v2/test/e2e/fixture/app"
+
+	. "github.com/argoproj/gitops-engine/pkg/sync/common"
+)
+
+func TestSimpleHydrator(t *testing.T) {
+	Given(t).
+		DrySourcePath("guestbook").
+		DrySourceRevision("HEAD").
+		SyncSourcePath("guestbook").
+		SyncSourceBranch("env/test").
+		When().
+		CreateApp().
+		Refresh(RefreshTypeNormal).
+		Wait("--hydrated").
+		Sync().
+		Then().
+		Expect(OperationPhaseIs(OperationSucceeded)).
+		Expect(SyncStatusIs(SyncStatusCodeSynced))
+}
+
+func TestHydrateTo(t *testing.T) {
+	Given(t).
+		DrySourcePath("guestbook").
+		DrySourceRevision("HEAD").
+		SyncSourcePath("guestbook").
+		SyncSourceBranch("env/test").
+		HydrateToBranch("env/test-next").
+		When().
+		CreateApp().
+		Refresh(RefreshTypeNormal).
+		Wait("--hydrated").
+		Then().
+		Given().
+		// Async so we don't fail immediately on the error
+		Async(true).
+		When().
+		Sync().
+		Wait("--operation").
+		Then().
+		// Fails because we hydrated to env/test-next but not to env/test.
+		Expect(OperationPhaseIs(OperationError)).
+		When().
+		// Will now hydrate to the sync source branch.
+		AppSet("--hydrate-to-branch", "").
+		Refresh(RefreshTypeNormal).
+		Wait("--hydrated").
+		Sync().
+		Wait("--operation").
+		Then().
+		Expect(OperationPhaseIs(OperationSucceeded)).
+		Expect(SyncStatusIs(SyncStatusCodeSynced))
+}
+
+func TestAddingApp(t *testing.T) {
+	// Make sure that if we add another app targeting the same sync branch, it hydrates correctly.
+	Given(t).
+		Name("test-adding-app-1").
+		DrySourcePath("guestbook").
+		DrySourceRevision("HEAD").
+		SyncSourcePath("guestbook-1").
+		SyncSourceBranch("env/test").
+		When().
+		CreateApp().
+		Refresh(RefreshTypeNormal).
+		Wait("--hydrated").
+		Sync().
+		Then().
+		Expect(OperationPhaseIs(OperationSucceeded)).
+		Expect(SyncStatusIs(SyncStatusCodeSynced)).
+		Given().
+		Name("test-adding-app-2").
+		DrySourcePath("guestbook").
+		DrySourceRevision("HEAD").
+		SyncSourcePath("guestbook-2").
+		SyncSourceBranch("env/test").
+		When().
+		CreateApp().
+		Refresh(RefreshTypeNormal).
+		Wait("--hydrated").
+		Sync().
+		Then().
+		Expect(OperationPhaseIs(OperationSucceeded)).
+		Expect(SyncStatusIs(SyncStatusCodeSynced)).
+		// Clean up the apps manually since we used custom names.
+		When().
+		Delete(true).
+		Then().
+		Expect(DoesNotExist()).
+		Given().
+		Name("test-adding-app-1").
+		When().
+		Delete(true).
+		Then().
+		Expect(DoesNotExist())
+}

util/argo/argo.go

@@ -231,6 +231,7 @@ func RefreshApp(appIf v1alpha1.ApplicationInterface, name string, refreshType ar
 		"metadata": map[string]interface{}{
 			"annotations": map[string]string{
 				argoappv1.AnnotationKeyRefresh: string(refreshType),
+				argoappv1.AnnotationKeyHydrate: "normal",
 			},
 		},
 	}
@@ -417,6 +418,12 @@ func validateRepo(ctx context.Context,
 		}
 	}
 
+	// If using the source hydrator, check the dry source instead of the sync source, since the sync source branch may
+	// not exist yet.
+	if app.Spec.SourceHydrator != nil {
+		sources = []argoappv1.ApplicationSource{app.Spec.SourceHydrator.GetDrySource()}
+	}
+
 	refSources, err := GetRefSources(ctx, sources, app.Spec.Project, db.GetRepository, []string{}, false)
 	if err != nil {
 		return nil, fmt.Errorf("error getting ref sources: %w", err)
@@ -555,11 +562,46 @@ func validateSourcePermissions(source argoappv1.ApplicationSource, hasMultipleSo
 	return conditions
 }
 
+func validateSourceHydrator(hydrator *argoappv1.SourceHydrator) []argoappv1.ApplicationCondition {
+	var conditions []argoappv1.ApplicationCondition
+	if hydrator.DrySource.RepoURL == "" {
+		conditions = append(conditions, argoappv1.ApplicationCondition{
+			Type:    argoappv1.ApplicationConditionInvalidSpecError,
+			Message: "spec.sourceHydrator.drySource.repoURL is required",
+		})
+	}
+	if hydrator.SyncSource.TargetBranch == "" {
+		conditions = append(conditions, argoappv1.ApplicationCondition{
+			Type:    argoappv1.ApplicationConditionInvalidSpecError,
+			Message: "spec.sourceHydrator.syncSource.targetBranch is required",
+		})
+	}
+	if hydrator.HydrateTo != nil && hydrator.HydrateTo.TargetBranch == "" {
+		conditions = append(conditions, argoappv1.ApplicationCondition{
+			Type:    argoappv1.ApplicationConditionInvalidSpecError,
+			Message: "when spec.sourceHydrator.hydrateTo is set, spec.sourceHydrator.hydrateTo.path is required",
+		})
+	}
+	return conditions
+}
+
 // ValidatePermissions ensures that the referenced cluster has been added to Argo CD and the app source repo and destination namespace/cluster are permitted in app project
 func ValidatePermissions(ctx context.Context, spec *argoappv1.ApplicationSpec, proj *argoappv1.AppProject, db db.ArgoDB) ([]argoappv1.ApplicationCondition, error) {
 	conditions := make([]argoappv1.ApplicationCondition, 0)
 
-	if spec.HasMultipleSources() {
+	if spec.SourceHydrator != nil {
+		condition := validateSourceHydrator(spec.SourceHydrator)
+		if len(condition) > 0 {
+			conditions = append(conditions, condition...)
+			return conditions, nil
+		}
+		if !proj.IsSourcePermitted(spec.SourceHydrator.GetDrySource()) {
+			conditions = append(conditions, argoappv1.ApplicationCondition{
+				Type:    argoappv1.ApplicationConditionInvalidSpecError,
+				Message: fmt.Sprintf("application repo %s is not permitted in project '%s'", spec.GetSource().RepoURL, spec.Project),
+			})
+		}
+	} else if spec.HasMultipleSources() {
 		for _, source := range spec.Sources {
 			condition := validateSourcePermissions(source, spec.HasMultipleSources())
 			if len(condition) > 0 {